CriticalCVE-2026-102560

    Libsoup: libsoup: heap buffer overflow during outgoing permessage-deflate buffer growth (CVE-2026-102560)

    Published Last modified Sources: CVE.org, SUSE, Msrc Update Guide, BSI

    What is affected, what to do

    A flaw was found in libsoup. When the permessage-deflate WebSocket extension compresses a very large outgoing message, truncated size calculations used for GByteArray growth could wrap, causing zlib to write past the allocated buffer and resulting in a heap buffer overflow.

    Update Red Hat Enterprise Linux 10 to version 0:3.6.5-3.el10_2.20, Red Hat Enterprise Linux 9 to version 0:2.72.0-16.el9_8.8.

    Affected
    • Red Hat Enterprise Linux 10 lt *..0:3.6.5-3.el10_2.20
    • Red Hat Enterprise Linux 9 lt *..0:2.72.0-16.el9_8.8
    Fixed in
    • Red Hat Enterprise Linux 10 0:3.6.5-3.el10_2.20
    • Red Hat Enterprise Linux 9 0:2.72.0-16.el9_8.8

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

    Metrics

    9.8

    Priority

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

    Source: NVD, CVSS v3

    8.6

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: CVE.org, SUSE, Msrc Update Guide, BSI

    0.4 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 36.1

    Show all metrics
    Severity
    Critical
    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
    83.43 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
    9.8 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
    8.6
    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
    0.4 %
    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
    36.1
    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 29 September 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-125

    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 libsoup. When the permessage-deflate WebSocket extension compresses a very large outgoing message, truncated size calculations used for GByteArray growth could wrap, causing zlib to write past the allocated buffer and resulting in a heap buffer overflow.

    Source: NVD (NIST), cvelistv5, suse_csaf, Microsoft Security Update Guide, BSI WID Portal, BSI CSAF

    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
    Red HatRed Hat Enterprise Linux 10
    • < 0:3.6.5-3.el10_2.20
    • 0:3.6.5-3.el10_2.20
    Red HatRed Hat Enterprise Linux 6
    • —
    • —
    Red HatRed Hat Enterprise Linux 7
    • —
    • —
    Red HatRed Hat Enterprise Linux 8
    • —
    • —
    Red HatRed Hat Enterprise Linux 9
    • < 0:2.72.0-16.el9_8.8
    • 0:2.72.0-16.el9_8.8
    gnomelibsoup
    • < 3.7.3
    • 3.7.3
    Red HatEnterprise Linux
    • 9
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxredhatenterprise_linux10.0
    Linuxredhatenterprise_linux7.0
    Linuxredhatenterprise_linux8.0
    Linuxredhatenterprise_linux9.0

    Weakness classes (CWE)

    • CWE-125Out-of-bounds Read

      Base

      The product reads data past the end, or before the beginning, of the intended buffer.

      Entry at MITRE CWE-125

    References & sources

    • access.redhat.comsecurity/cve/CVE-2026-102560Vulnerability database, x_refsource_REDHAT, Mitigation, Third-party advisory
    • bugzilla.redhat.comRHBZ#2543296Issue tracking, x_refsource_REDHAT, Issue tracking, Patch, Third-party advisory
    • access.redhat.comRHSA-2026:83384Vendor advisory, x_refsource_REDHAT, Third-party advisory
    • access.redhat.comRHSA-2026:83618Vendor advisory, x_refsource_REDHAT, Third-party advisory

    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

      1 individual change: Affected versions (publisher)

      Show the original change
      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/2026/102xxx/CVE-2026-102560.json">CVE-2026-102560</a>

      Source identifier: secalert@redhat.com

    2. Initial analysis by NVDNVD

      Newly listed as affected:

      CVSS V3.1: AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

      Show 6 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      CVSSadded
      —
      AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
      Product configurationadded
      —
      OR *cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:* *cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:* *cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:* *cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:* *cpe:2.3:a:gnome:libsoup:*:*:*:*:*:*:*:* versions up to (excluding) 3.7.3
      Reference typeadded
      —
      Red Hat, Inc.: https://access.redhat.com/errata/RHSA-2026:83384 Types: Third Party Advisory
      Reference typeadded
      —
      Red Hat, Inc.: https://access.redhat.com/errata/RHSA-2026:83618 Types: Third Party Advisory
      Reference typeadded
      —
      Red Hat, Inc.: https://access.redhat.com/security/cve/CVE-2026-102560 Types: Mitigation, Third Party Advisory
      Reference typeadded
      —
      Red Hat, Inc.: https://bugzilla.redhat.com/show_bug.cgi?id=2543296 Types: Issue Tracking, Patch, Third Party Advisory

      Source identifier: nvd@nist.gov

    3. Record modifiedRed Hat

      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/2026/102xxx/CVE-2026-102560.json">CVE-2026-102560</a>
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:83618

      Source identifier: secalert@redhat.com

    4. Record modifiedRed Hat

      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/2026/102xxx/CVE-2026-102560.json">CVE-2026-102560</a>
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:83384

      Source identifier: secalert@redhat.com

    5. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: none known, automatable: yes

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      SSVC assessmentadded
      —
      {"id":"CVE-2026-102560","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-09-29T19:51:42.455534Z"}

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

    Show one older change

    1. ReceivedRed Hat

      CVSS V3.1: AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

      Weakness type: CWE-125

      Description added or changed

      Show 6 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      A flaw was found in libsoup. When the permessage-deflate WebSocket extension compresses a very large outgoing message, truncated size calculations used for GByteArray growth could wrap, causing zlib to write past the allocated buffer and resulting in a heap buffer overflow.
      CVSSadded
      —
      AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
      Weakness type (CWE)added
      —
      CWE-125
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/102xxx/CVE-2026-102560.json">CVE-2026-102560</a>
      Referenceadded
      —
      https://access.redhat.com/security/cve/CVE-2026-102560
      Referenceadded
      —
      https://bugzilla.redhat.com/show_bug.cgi?id=2543296

      Source identifier: secalert@redhat.com

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