HighCVE-2026-42587

    Netty: Allocation of Resources Without Limits or Throttling (CVE-2026-42587)

    Published Last modified Sources: Red Hat, BSI, SUSE, OSV, CVE.org, EUVD

    What is affected, what to do

    Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, HttpContentDecompressor accepts a maxAllocation parameter to limit decompression buffer size and prevent decompression bomb attacks.

    An exploit is publicly available. Update Netty to version 4.1.133.Final, Io.netty Netty-codec-http to version 4.1.133.Final, Io.netty Netty-codec-http2 to version 4.1.133.Final.

    Affected
    • Netty gte 4.2.0.Alpha1, < 4.2.13.Final..*
    • Netty lt *..4.1.133.Final
    • Io.netty Netty-codec-http gte 4.2.0.Alpha1, < 4.2.13.Final..*
    • Io.netty Netty-codec-http lt *..4.1.133.Final
    • Io.netty Netty-codec-http2 gte 4.2.0.Alpha1, < 4.2.13.Final..*
    • Io.netty Netty-codec-http2 lt *..4.1.133.Final
    Fixed in
    • Netty 4.1.133.Final
    • Io.netty Netty-codec-http 4.1.133.Final
    • Io.netty Netty-codec-http2 4.1.133.Final

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    7.5

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v3

    7.5

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: Red Hat, BSI, SUSE, OSV, CVE.org, EUVD

    1.0 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 62.3

    Show all metrics
    Severity
    High
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    86.04 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    PoC (publicly reported)
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    7.5 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    7.5
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    1.0 %
    Low — model estimates < 1% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    62.3
    High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    —
    Published
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-400, CWE-770

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, HttpContentDecompressor accepts a maxAllocation parameter to limit decompression buffer size and prevent decompression bomb attacks. This limit is correctly enforced for gzip and deflate encodings via ZlibDecoder, but is silently ignored when the content encoding is br (Brotli), zstd, or snappy. An attacker can bypass the configured decompression limit by sending a compressed payload with Content-Encoding: br instead of Content-Encoding: gzip, causing unbounded memory allocation and out-of-memory denial of service. The same vulnerability exists in DelegatingDecompressorFrameListener for HTTP/2 connections. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

    Source: redhat_csaf, BSI WID Portal, BSI CSAF, suse_csaf, OSV (Open Source Vulnerabilities), cvelistv5, ENISA EUVD, NVD (NIST), CVE.org (MITRE)

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    io.nettynetty-codec-http
    • ≥ 4.2.0.Alpha1, < 4.2.13.Final
    • < 4.1.133.Final
    • —
    • 4.1.133.Final
    io.nettynetty-codec-http2
    • < 4.1.133.Final
    • ≥ 4.2.0.Alpha1, < 4.2.13.Final
    • 4.1.133.Final
    • —
    nettynetty
    • < 4.1.133.Final
    • ≥ 4.2.0.Alpha1, < 4.2.13.Final
    • 4.2.0 – < 4.2.13
    • < 4.1.133
    • 4.1.133.Final
    • —
    • 4.2.13
    • 4.1.133
    OracleCommerce
    • 11.4.0
    • —
    OracleCommunications
    • 25.2.0.0.10
    • 8.0.1
    • 8.0.0
    • 7.5.0-7.5.1
    • 7.6.0-7.8.0
    • 6.1.1-7.0.0
    • 7.4.1
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    OracleFusion Middleware
    • 1.4.20
    • 3.2.18
    • 12.2.1.4.0
    • 14.1.1.0.0
    • 4.5.0
    • 4.5.3
    • 12.2.1.19.0
    • 14.1.2.0.0
    • 15.1.1.0.0
    • 1.4.19
    • 8.5.8
    • 3.2.19
    • 3.2.20
    • 14.1.2.1.0
    • 4.5.1
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    OracleNoSQL Database
    • 25.3.24
    • 23.3.41
    • 24.4.14
    • —
    • —
    • —
    OracleRetail Applications
    • 21.0.0-25.0.0
    • 14.1.3.2
    • 16.0.3
    • 19.0.1
    • 13.2.8
    • 21.0.5-25.0.1
    • —
    • —
    • —
    • —
    • —
    • —
    OracleTimesTen In-Memory Database
    • 26.1.1.1.0
    • 22.1.1.1.0
    • —
    • —
    OracleUtilities Applications
    • 4.4.0.4.0
    • 25.12.0.0.0-25.12.0.0.2
    • 4.5.0.1.1
    • 2.6.0.2.0-2.6.0.2.10
    • 2.5.0.1.0-2.5.0.1.18
    • 2.4.0.1.0-2.4.0.1.33
    • —
    • —
    • —
    • —
    • —
    • —

    Vendors and products

    Weakness classes (CWE)

    • CWE-400Uncontrolled Resource Consumption

      Class

      The product does not properly control the allocation and maintenance of a limited resource.

      Entry at MITRE CWE-400

    • CWE-770Allocation of Resources Without Limits or Throttling

      Base

      The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

      Entry at MITRE CWE-770

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    Reference tagged as exploitgithub.com (opens in a new tab)PoC (publicly reported)reported, not verified—

    References & sources

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    1. Record modifiedRed Hat ADP

      Show 4 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/42xxx/CVE-2026-42587.json">CVE-2026-42587</a>
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:53645
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:53646
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:53806
      —

      Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

    2. Record modifiedRed Hat ADP

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:49701

      Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

    3. Record modifiedRed Hat ADP

      Show 3 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/42xxx/CVE-2026-42587.json">CVE-2026-42587</a>
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:66488
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:66545

      Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

    4. Record modifiedRed Hat ADP

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/42xxx/CVE-2026-42587.json">CVE-2026-42587</a>
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:65126

      Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

    5. Record modifiedRed Hat ADP

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/42xxx/CVE-2026-42587.json">CVE-2026-42587</a>
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:49700

      Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

    Show 9 older changes

    1. Record modifiedGitHub

      Show 3 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://github.com/netty/netty/security/advisories/GHSA-f6hv-jmp6-3vwv
      Referenceremoved
      https://github.com/netty/netty/security/advisories/GHSA-f6hv-jmp6-3vwv
      —
      Reference typeremoved
      https://github.com/netty/netty/security/advisories/GHSA-f6hv-jmp6-3vwv Types: Exploit, Mitigation, Vendor Advisory
      —

      Source identifier: security-advisories@github.com

    2. Record modifiedCISA ADP

      Show 3 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
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      https://github.com/netty/netty/security/advisories/GHSA-f6hv-jmp6-3vwv
      Referenceremoved
      https://github.com/netty/netty/security/advisories/GHSA-f6hv-jmp6-3vwv
      —
      Reference typeremoved
      https://github.com/netty/netty/security/advisories/GHSA-f6hv-jmp6-3vwv Types: Exploit, Mitigation, Vendor Advisory
      —

      Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

    3. Record modifiedRed Hat ADP

      Show 33 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/42xxx/CVE-2026-42587.json">CVE-2026-42587</a>
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:23808
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:24502
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:25123
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      https://access.redhat.com/errata/RHSA-2026:28010
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      https://access.redhat.com/errata/RHSA-2026:34608
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      https://access.redhat.com/errata/RHSA-2026:36820
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      https://access.redhat.com/errata/RHSA-2026:37390
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      https://access.redhat.com/errata/RHSA-2026:41951
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:42644
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:50085
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:53644
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:53806
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:54435
      Referenceadded
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      https://access.redhat.com/security/cve/CVE-2026-42587
      Referenceadded
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      https://bugzilla.redhat.com/show_bug.cgi?id=2477220
      Referenceadded
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      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42587.json
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:23808
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      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:24502
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      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:25123
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      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:28010
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      https://access.redhat.com/errata/RHSA-2026:34608
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      https://access.redhat.com/errata/RHSA-2026:36820
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      https://access.redhat.com/errata/RHSA-2026:37390
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      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:41951
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      https://access.redhat.com/errata/RHSA-2026:42644
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      https://access.redhat.com/errata/RHSA-2026:50085
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      https://access.redhat.com/errata/RHSA-2026:53644
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      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:53806
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      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:54435
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      Referenceremoved
      https://access.redhat.com/security/cve/CVE-2026-42587
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      Referenceremoved
      https://bugzilla.redhat.com/show_bug.cgi?id=2477220
      —
      Referenceremoved
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42587.json
      —

      Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

    4. Record modifiedRed Hat ADP

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:50085
      Affected versions (publisher)changed
      Cryostat 4 on RHEL 9, Cryostat 4 on RHEL 9, Cryostat 4 on RHEL 9 (+68)
      Cryostat 4 on RHEL 9, Cryostat 4 on RHEL 9, Cryostat 4 on RHEL 9 (+69)

      Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

    5. Record modifiedRed Hat ADP

      1 individual change: Affected versions (publisher)

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)changed
      Cryostat 4 on RHEL 9, Cryostat 4 on RHEL 9, Cryostat 4 on RHEL 9 (+68)
      Cryostat 4 on RHEL 9, Cryostat 4 on RHEL 9, Cryostat 4 on RHEL 9 (+68)

      Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

    6. Record modifiedRed Hat ADP

      1 individual change: Affected versions (publisher)

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)changed
      Cryostat 4 on RHEL 9, Cryostat 4 on RHEL 9, Cryostat 4 on RHEL 9 (+68)
      Cryostat 4 on RHEL 9, Cryostat 4 on RHEL 9, Cryostat 4 on RHEL 9 (+68)

      Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

    7. Record modifiedRed Hat ADP

      Show 3 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:41951
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:42644
      Affected versions (publisher)changed
      Cryostat 4 on RHEL 9, Cryostat 4 on RHEL 9, Cryostat 4 on RHEL 9 (+69)
      Cryostat 4 on RHEL 9, Cryostat 4 on RHEL 9, Cryostat 4 on RHEL 9 (+68)

      Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

    8. Record modifiedRed Hat ADP

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:36820
      Affected versions (publisher)changed
      Cryostat 4 on RHEL 9, Red Hat OpenShift Dev Spaces 3.28, Red Hat build of Quarkus 3.27.4 (+26)
      Cryostat 4 on RHEL 9, Red Hat OpenShift Dev Spaces 3.28, Red Hat OpenShift Dev Spaces 3.29 (+26)

      Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

    9. Record modifiedRed Hat ADP

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:34608
      Affected versions (publisher)changed
      Cryostat 4 on RHEL 9, Red Hat OpenShift Dev Spaces 3.28, Red Hat build of Quarkus 3.27.4 (+25)
      Cryostat 4 on RHEL 9, Red Hat OpenShift Dev Spaces 3.28, Red Hat build of Quarkus 3.27.4 (+26)

      Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

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