HighCVE-2026-57188

    Asterisk: Stack buffer overflow in res_xmpp XMPP namespace prefix handling (CVE-2026-57188)

    Published Last modified Sources: BSI, CVE.org

    What is affected, what to do

    Asterisk is an open source private branch exchange and telephony toolkit. Prior to Asterisk 20.20.1, 21.12.3, 22.10.1, 23.4.1 and Certified Asterisk 20.7-cert11, 22.8-cert3, an authenticated attacker may cause a stack buffer overflow in `res_xmpp` `XMPP namespace prefix` handling using carefully crafted packets.

    Update Asterisk to version 20.20.1, Asterisk Certified-asterisk to version 20.7-cert11.

    Affected
    • Asterisk gte 21.0.0-pre1, < 21.12.3..*
    • Asterisk lt *..20.20.1
    • Asterisk Certified-asterisk gte 22.8-cert1-pre1, < 22.8-cert3..*
    • Asterisk Certified-asterisk lt *..20.7-cert11
    Fixed in
    • Asterisk 20.20.1
    • Asterisk Certified-asterisk 20.7-cert11

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

    Metrics

    7.1

    Priority

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

    Source: Vendor (CNA), CVSS v4

    7.1

    CVSS v4

    Severity High on the scale from 0 to 10.

    Source: BSI, CVE.org

    0.5 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 44.2

    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
    81.11 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
    7.1 Methodology
    CVSS v4

    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
    7.1
    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
    0.5 %
    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
    44.2
    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
    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-787

    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

    Asterisk is an open source private branch exchange and telephony toolkit. Prior to Asterisk 20.20.1, 21.12.3, 22.10.1, 23.4.1 and Certified Asterisk 20.7-cert11, 22.8-cert3, an authenticated attacker may cause a stack buffer overflow in `res_xmpp` `XMPP namespace prefix` handling using carefully crafted packets. The `res_xmpp` module must be loaded, an XMPP connection must be configured in `xmpp.conf`, and the attacker must have an XMPP account on the same or a federated server. This issue is fixed in Asterisk 20.20.1, 21.12.3, 22.10.1, 23.4.1 and Certified Asterisk 20.7-cert11, 22.8-cert3.

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

    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
    asteriskasterisk
    • ≥ 21.0.0-pre1, < 21.12.3
    • < 20.20.1
    • —
    • 20.20.1
    asteriskcertified-asterisk
    • < 20.7-cert11
    • ≥ 22.8-cert1-pre1, < 22.8-cert3
    • 20.7-cert11
    • —

    Vendors and products

    Weakness classes (CWE)

    • CWE-787Out-of-bounds Write

      Base

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

      Entry at MITRE CWE-787

    References & sources

    • github.comasterisk/asterisk/security/advisories/GHSA-mxgm-8c6f-5p8fx_refsource_CONFIRM
    • github.comasterisk/asterisk/commit/12072a559f592736a44dd9fbe1594e84714edf…x_refsource_MISC
    • github.comasterisk/asterisk/commit/1328dbb503da4aa11a480a9c28e170f17e5f4e…x_refsource_MISC
    • github.comasterisk/asterisk/commit/3c4b08cf94eeaa3faefb3ae6c2d6ce1bd9747a…x_refsource_MISC
    • github.comasterisk/asterisk/commit/433102c16b8edfc31d28c96166fef03fe72fb9…x_refsource_MISC
    • github.comasterisk/asterisk/commit/5e626250628b2579530f3f17e7b0aa37d08287…x_refsource_MISC
    • github.comasterisk/asterisk/commit/d570a85e45153a36919ace5d0ab06a195b30f9…x_refsource_MISC
    • github.comasterisk/asterisk/commit/e329a6803ac5214028f98cc5f0b7167d66e32c…x_refsource_MISC
    • github.comasterisk/asterisk/releases/tag/20.20.1x_refsource_MISC
    • github.comasterisk/asterisk/releases/tag/21.12.3x_refsource_MISC
    • github.comasterisk/asterisk/releases/tag/22.10.1x_refsource_MISC
    • github.comasterisk/asterisk/releases/tag/23.4.1x_refsource_MISC
    • github.comasterisk/asterisk/releases/tag/certified-20.7-cert11x_refsource_MISC
    • github.comasterisk/asterisk/releases/tag/certified-22.8-cert3x_refsource_MISC
    • github.comasterisk/asterisk/tree/24.0.0-pre1x_refsource_MISC

    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. ReceivedGitHub

      CVSS V4.0: AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

      Weakness type: CWE-787

      Description added or changed

      Show 19 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      Asterisk is an open source private branch exchange and telephony toolkit. Prior to Asterisk 20.20.1, 21.12.3, 22.10.1, 23.4.1 and Certified Asterisk 20.7-cert11, 22.8-cert3, an authenticated attacker may cause a stack buffer overflow in `res_xmpp` `XMPP namespace prefix` handling using carefully crafted packets. The `res_xmpp` module must be loaded, an XMPP connection must be configured in `xmpp.conf`, and the attacker must have an XMPP account on the same or a federated server. This issue is fixed in Asterisk 20.20.1, 21.12.3, 22.10.1, 23.4.1 and Certified Asterisk 20.7-cert11, 22.8-cert3.
      CVSSadded
      —
      AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
      Weakness type (CWE)added
      —
      CWE-787
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/57xxx/CVE-2026-57188.json">CVE-2026-57188</a>
      Referenceadded
      —
      https://github.com/asterisk/asterisk/commit/12072a559f592736a44dd9fbe1594e84714edfb4
      Referenceadded
      —
      https://github.com/asterisk/asterisk/commit/1328dbb503da4aa11a480a9c28e170f17e5f4e84
      Referenceadded
      —
      https://github.com/asterisk/asterisk/commit/3c4b08cf94eeaa3faefb3ae6c2d6ce1bd9747a13
      Referenceadded
      —
      https://github.com/asterisk/asterisk/commit/433102c16b8edfc31d28c96166fef03fe72fb923
      Referenceadded
      —
      https://github.com/asterisk/asterisk/commit/5e626250628b2579530f3f17e7b0aa37d082873b
      Referenceadded
      —
      https://github.com/asterisk/asterisk/commit/d570a85e45153a36919ace5d0ab06a195b30f9d1
      Referenceadded
      —
      https://github.com/asterisk/asterisk/commit/e329a6803ac5214028f98cc5f0b7167d66e32c08
      Referenceadded
      —
      https://github.com/asterisk/asterisk/releases/tag/20.20.1
      Referenceadded
      —
      https://github.com/asterisk/asterisk/releases/tag/21.12.3
      Referenceadded
      —
      https://github.com/asterisk/asterisk/releases/tag/22.10.1
      Referenceadded
      —
      https://github.com/asterisk/asterisk/releases/tag/23.4.1
      Referenceadded
      —
      https://github.com/asterisk/asterisk/releases/tag/certified-20.7-cert11
      Referenceadded
      —
      https://github.com/asterisk/asterisk/releases/tag/certified-22.8-cert3
      Referenceadded
      —
      https://github.com/asterisk/asterisk/security/advisories/GHSA-mxgm-8c6f-5p8f
      Referenceadded
      —
      https://github.com/asterisk/asterisk/tree/24.0.0-pre1

      Source identifier: security-advisories@github.com

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