HighCVE-2026-109413

    Symfony: Unbounded Recursion in the YAML Inline Lexer Lets a Single Document Crash the Process (CVE-2026-109413)

    Published Last modified Sources: CVE.org, OSV, Hersteller, BSI

    What is affected, what to do

    Update open source Snipe-IT to version 8.8.1.

    Affected
    • open source Snipe-IT < *..8.8.1
    Fixed in
    • open source Snipe-IT 8.8.1

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

    Metrics

    8.7

    Priority

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

    Source: Vendor (CNA), CVSS v4

    8.7

    CVSS v4

    Severity High on the scale from 0 to 10.

    Source: CVE.org, OSV, Hersteller, BSI

    0.4 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 33.8

    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
    82.59 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
    8.7 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
    8.7
    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
    33.8
    Elevated — this CVE ranks above at least 10% of all CVEs scored today.
    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 15 October 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-674

    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

    Description

    Yaml\Parser::lexInlineStructure() recursed through lexInlineMapping() and lexInlineSequence() for every { and [ of an inline collection, without entering the nesting level that the rest of the parser bounds with maxNestingLevel. A document made of deeply nested inline collections, such as [[[[...]]]], exhausted the stack while it was being lexed: depending on the PHP version and its stack settings, the process crashed or the request ended with a fatal error.

    Any code parsing untrusted YAML is affected. That includes #[MapRequestPayload] when the Yaml component is installed and the endpoint does not restrict acceptFormat: a single unauthenticated request with a YAML content type is enough.

    Resolution

    The inline lexer now enters and leaves the same nesting level as the rest of the parser, so nested inline collections are bounded by maxNestingLevel, and the parser raises a ParseException beyond it.

    The patches for this issue are available here for branch 5.4 (and forward-ported to 6.4, 7.4, 8.1 and 8.2).

    Credits

    We would like to thank Nicolas Grekas for reporting the issue and providing the fix.

    References

    Source: cvelistv5, NVD (NIST), OSV (Open Source Vulnerabilities), GitHub Security Advisories, 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
    sensiolabssymfony
    • —
    • —
    Open SourceSnipe-IT
    • < 8.8.1
    • 8.8.1
    composersymfony/symfony
    • >= 2.0.0, < 5.4.54
    • >= 6.0.0, < 6.4.45
    • >= 8.0.0, < 8.1.6
    • >= 7.0.0, < 7.4.18
    • 5.4.54
    • 6.4.45
    • 8.1.6
    • 7.4.18
    composersymfony/yaml
    • >= 8.0.0, < 8.1.6
    • >= 2.0.0, < 5.4.54
    • >= 7.0.0, < 7.4.18
    • >= 6.0.0, < 6.4.45
    • 8.1.6
    • 5.4.54
    • 7.4.18
    • 6.4.45
    packagistsymfony/symfony
    • v7.4.1
    • v8.0.3
    • v5.4.38
    • v2.7.52
    • v5.4.5
    • v6.1.0
    • v2.5.0-BETA1
    • v4.4.0-BETA1
    • v6.0.9
    • v6.4.32
    • v6.2.10
    • v3.4.30
    • v2.8.52
    • v2.8.22
    • v7.0.4
    • v3.3.4
    • v2.8.11
    • v8.0.2
    • v3.4.18
    • v4.4.4
    • v7.4.5
    • v5.4.19
    • v3.4.0-RC2
    • v4.4.26
    • v4.0.8
    • v2.6.6
    • v6.4.1
    • v4.4.31
    • v5.4.0-RC1
    • v4.4.24
    • v6.0.3
    • v6.1.11
    • v6.4.34
    • v2.6.11
    • v5.1.6
    • v5.0.0
    • v3.2.0-RC1
    • v5.2.12
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —

    Vendors and products

    Weakness classes (CWE)

    • CWE-674Uncontrolled Recursion

      Class

      The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.

      Entry at MITRE CWE-674

    References & sources

    • github.comsymfony/symfony/security/advisories/GHSA-2v3c-qxhr-7vpvThird-party advisory, web
    • symfony.comblog/cve-2026-109413-unbounded-recursion-in-the-yaml-inline-lex…Vendor advisory, web
    • github.comsymfony/symfony/pull/65688Patch, web
    • NVD (NIST)vuln/detail/CVE-2026-109413advisory
    • github.comsymfony/symfony/commit/116287c3b5bc057e7a0420d2e52d384e14ea9417web
    • github.comsymfony/symfony/commit/2a8bf9c58d862b0c76a35ce288d1ba6a27223aadweb
    • github.comsymfony/symfony/commit/8fb436fed9658a79d220e9f2b1ba8a2095559018web
    • github.comsymfony/symfony/commit/ab61e6cfd35042f16840a00f485eab2481dd4c2aweb
    • github.comFriendsOfPHP/security-advisories/blob/master/symfony/symfony/CV…web
    • github.comFriendsOfPHP/security-advisories/blob/master/symfony/yaml/CVE-2…web
    • github.comsymfony/symfonypackage
    • github.comsymfony/symfony/releases/tag/v5.4.54web
    • github.comsymfony/symfony/releases/tag/v6.4.45web
    • github.comsymfony/symfony/releases/tag/v7.4.18web
    • github.comsymfony/symfony/releases/tag/v8.1.6web
    • symfony.comcve-2026-109413web

    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 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-2026-109413","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-10-15T18:06:37.552332Z"}

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

    2. Record modified596c5446…

      Description added or changed

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionchanged
      In Symfony YAML prior to versions 5.4.54, 6.4.45, 7.4.18, and 8.1.6, Yaml\Parser::lexInlineStructure() recursed through lexInlineMapping() and lexInlineSequence() for every { and [ of an inline collection, without entering the nesting level that the rest of the parser bounds with maxNestingLevel. A document made of deeply nested inline collections, such as [[[[...]]]], exhausted the stack while it was being lexed: depending on the PHP version and its stack settings, the process crashed or the request ended with a fatal error. Any code parsing untrusted YAML is affected. That includes #[MapRequestPayload] when the Yaml component is installed and the endpoint does not restrict acceptFormat: a single unauthenticated request with a YAML content type is enough. This issue affects symfony/yaml prior to v5.4.54, v6.0.0-BETA1 prior to v6.4.45, v7.0.0-BETA1 prior to v7.4.18, and v8.0.0-BETA1 prior to v8.1.6.
      In Symfony YAML prior to versions 5.4.54, 6.4.45, 7.4.18, and 8.1.6, Yaml\Parser::lexInlineStructure() recursed through lexInlineMapping() and lexInlineSequence() for every { and [ of an inline collection, without entering the nesting level that the rest of the parser bounds with maxNestingLevel. A document made of deeply nested inline collections, such as [[[[...]]]], exhausted the stack while it was being lexed: depending on the PHP version and its stack settings, the process crashed or the request ended with a fatal error. Any code parsing untrusted YAML is affected. That includes #[MapRequestPayload] when the Yaml component is installed and the endpoint does not restrict acceptFormat: a single unauthenticated request with a YAML content type is enough. This issue affects symfony/yaml through v5.4.53, v6.0.0-BETA1 through v6.4.44, v7.0.0-BETA1 through v7.4.17, and v8.0.0-BETA1 through v8.1.5.

      Source identifier: 596c5446-0ce5-4ba2-aa66-48b3b757a647

    3. Received596c5446…

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

      Weakness type: CWE-674

      Description added or changed

      Show 7 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      In Symfony YAML prior to versions 5.4.54, 6.4.45, 7.4.18, and 8.1.6, Yaml\Parser::lexInlineStructure() recursed through lexInlineMapping() and lexInlineSequence() for every { and [ of an inline collection, without entering the nesting level that the rest of the parser bounds with maxNestingLevel. A document made of deeply nested inline collections, such as [[[[...]]]], exhausted the stack while it was being lexed: depending on the PHP version and its stack settings, the process crashed or the request ended with a fatal error. Any code parsing untrusted YAML is affected. That includes #[MapRequestPayload] when the Yaml component is installed and the endpoint does not restrict acceptFormat: a single unauthenticated request with a YAML content type is enough. This issue affects symfony/yaml prior to v5.4.54, v6.0.0-BETA1 prior to v6.4.45, v7.0.0-BETA1 prior to v7.4.18, and v8.0.0-BETA1 prior to v8.1.6.
      CVSSadded
      —
      AV:N/AC:L/AT:N/PR:N/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-674
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/109xxx/CVE-2026-109413.json">CVE-2026-109413</a>
      Referenceadded
      —
      https://github.com/symfony/symfony/pull/65688
      Referenceadded
      —
      https://github.com/symfony/symfony/security/advisories/GHSA-2v3c-qxhr-7vpv
      Referenceadded
      —
      https://symfony.com/blog/cve-2026-109413-unbounded-recursion-in-the-yaml-inline-lexer-lets-a-single-document-crash-the-process

      Source identifier: 596c5446-0ce5-4ba2-aa66-48b3b757a647

    Embed badge

    Show the severity and KEV status of this vulnerability on your site – with a link back here. The image is updated hourly.

    Badge preview for CVE-2026-109413
    <a href="https://intel.neosec.eu/en/cve/CVE-2026-109413"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-109413.svg?lang=en" alt="CVE-2026-109413 – NEOSEC Intel" height="20"></a>