HighCVE-2026-2229

    Undici: Uncaught Exception (CVE-2026-2229)

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

    What is affected, what to do

    A flaw was found in the undici WebSocket client. A remote malicious server can exploit this vulnerability by sending a WebSocket frame with an invalid `server_max_window_bits` parameter within the permessage-deflate extension.

    Update Undici to version 6.24.0; 7.0.0 < 7.24.0.

    Affected
    • Undici lt *..6.24.0; 7.0.0 < 7.24.0
    Fixed in
    • Undici 6.24.0; 7.0.0 < 7.24.0

    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, CVE.org, OSV, BSI

    0.9 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 59.2

    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
    80.68 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
    no public PoC known
    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
    0.9 %
    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
    59.2
    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
    CISA assessment (SSVC)
    Exploitation: none known · automatable · Technical impact: partial
    Source: CISA Vulnrichment, as of 13 March 2026
    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-248, CWE-1284

    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

    A flaw was found in the undici WebSocket client. A remote malicious server can exploit this vulnerability by sending a WebSocket frame with an invalid `server_max_window_bits` parameter within the permessage-deflate extension. This improper validation causes the client's Node.js process to terminate, leading to a denial-of-service (DoS) condition for the client.

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

    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
    undiciundici
    • < 6.24.0; 7.0.0 < 7.24.0
    • 6.24.0; 7.0.0 < 7.24.0
    nodejsundici
    • < 6.24.0
    • 7.0.0 – < 7.24.0
    • 6.24.0
    • 7.24.0
    IBMApp Connect Enterprise
    • < 13.2.0
    • < 13.0.7.0
    • 13.2.0
    • 13.0.7.0
    IBMApp Connect Enterprise Certified Container Operator
    • < 12.0.24
    • 12.0.24
    npmundici
    • —
    • 7.0.0
    • —
    • —

    Vendors and products

    Weakness classes (CWE)

    • CWE-248Uncaught Exception

      Base

      An exception is thrown from a function, but it is not caught.

      Entry at MITRE CWE-248

    • CWE-1284Improper Validation of Specified Quantity in Input

      Base

      The product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties.

      Entry at MITRE CWE-1284

    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 modifiedOpenJS Foundation

      Show 15 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
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      https://cna.openjsf.org/security-advisories.html
      Referenceadded
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      https://datatracker.ietf.org/doc/html/rfc7692
      Referenceadded
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      https://github.com/nodejs/undici/security/advisories/GHSA-v9p9-hfj2-hcw8
      Referenceadded
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      https://hackerone.com/reports/3487486
      Referenceadded
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      https://nodejs.org/api/zlib.html#class-zlibinflateraw
      Referenceremoved
      https://cna.openjsf.org/security-advisories.html
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      Referenceremoved
      https://datatracker.ietf.org/doc/html/rfc7692
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      Referenceremoved
      https://github.com/nodejs/undici/security/advisories/GHSA-v9p9-hfj2-hcw8
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      Referenceremoved
      https://hackerone.com/reports/3487486
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      Referenceremoved
      https://nodejs.org/api/zlib.html#class-zlibinflateraw
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      Reference typeremoved
      https://cna.openjsf.org/security-advisories.html Types: Vendor Advisory
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      Reference typeremoved
      https://datatracker.ietf.org/doc/html/rfc7692 Types: Technical Description
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      Reference typeremoved
      https://github.com/nodejs/undici/security/advisories/GHSA-v9p9-hfj2-hcw8 Types: Vendor Advisory
      —
      Reference typeremoved
      https://hackerone.com/reports/3487486 Types: Permissions Required
      —
      Reference typeremoved
      https://nodejs.org/api/zlib.html#class-zlibinflateraw Types: Technical Description
      —

      Source identifier: ce714d77-add3-4f53-aff5-83d477b104bb

    2. Record modifiedRed Hat ADP

      Show 39 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/2026/2xxx/CVE-2026-2229.json">CVE-2026-2229</a>
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:13826
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:17789
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      https://access.redhat.com/errata/RHSA-2026:21772
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      https://access.redhat.com/errata/RHSA-2026:21931
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      https://access.redhat.com/errata/RHSA-2026:34342
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      https://access.redhat.com/errata/RHSA-2026:56431
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      https://access.redhat.com/errata/RHSA-2026:5807
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      https://access.redhat.com/errata/RHSA-2026:7080
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:7123
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      https://access.redhat.com/errata/RHSA-2026:7302
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:7310
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      https://access.redhat.com/errata/RHSA-2026:7350
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      https://access.redhat.com/errata/RHSA-2026:7670
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:7675
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:7983
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:9742
      Referenceadded
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      https://access.redhat.com/security/cve/CVE-2026-2229
      Referenceadded
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      https://bugzilla.redhat.com/show_bug.cgi?id=2447143
      Referenceadded
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      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-2229.json
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:13826
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:17789
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      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:21772
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      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:21931
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      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:34342
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:56431
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:5807
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:7080
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      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:7123
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:7302
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:7310
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:7350
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      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:7670
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      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:7675
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      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:7983
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      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:9742
      —
      Referenceremoved
      https://access.redhat.com/security/cve/CVE-2026-2229
      —
      Referenceremoved
      https://bugzilla.redhat.com/show_bug.cgi?id=2447143
      —
      Referenceremoved
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-2229.json
      —

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

    3. 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-2026:56431
      Affected versions (publisher)changed
      Cryostat 4 on RHEL 9, Cryostat 4 on RHEL 9, Red Hat Enterprise Linux 10 (+42)
      Cryostat 4 on RHEL 9, Cryostat 4 on RHEL 9, Red Hat Enterprise Linux 10 (+61)

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

    4. 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, Red Hat Enterprise Linux 10 (+42)
      Cryostat 4 on RHEL 9, Cryostat 4 on RHEL 9, Red Hat Enterprise Linux 10 (+42)

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

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