MediumCVE-2026-102277

    brace-expansion: Quadratic-time expansion of the `{a},b}` rewrite causes CPU denial of service (CVE-2026-102277)

    Published Last modified Sources: Red Hat, CVE.org, Hersteller, OSV, Msrc Update Guide

    What is affected, what to do

    A flaw was found in brace-expansion. A remote attacker can cause a Denial of Service (DoS) by supplying specially crafted string patterns with repeated closing braces.

    Update juliangruber brace-expansion to version 1.1.21.

    Affected
    • juliangruber brace-expansion gte 2.0.0, < 2.1.7..*
    • juliangruber brace-expansion lt *..1.1.21
    Fixed in
    • juliangruber brace-expansion 1.1.21

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

    Metrics

    5.3

    Priority

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

    Source: Vendor (CNA), CVSS v3

    5.3

    CVSS v3

    Severity Medium on the scale from 0 to 10.

    Source: Red Hat, CVE.org, Hersteller, OSV, Msrc Update Guide

    0.4 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 37.1

    Show all metrics
    Severity
    Medium
    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
    66.53 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
    5.3 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
    5.3
    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
    37.1
    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-400, CWE-407

    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
    Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
    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 brace-expansion. A remote attacker can cause a Denial of Service (DoS) by supplying specially crafted string patterns with repeated closing braces. Processing these malformed patterns causes the string expansion logic to repeatedly rescan the entire input, leading to excessive processor and memory consumption that can temporarily block the application event loop.

    Source: redhat_csaf, NVD (NIST), GitHub Security Advisories, OSV (Open Source Vulnerabilities), cvelistv5, Microsoft Security Update Guide

    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
    juliangruberbrace-expansion
    • ≥ 2.0.0, < 2.1.7
    • < 1.1.21
    • —
    • 1.1.21
    npmbrace-expansion
    • >= 2.0.0, < 2.1.7
    • < 1.1.21
    • >= 4.0.0, < 5.0.12
    • >= 3.0.0, < 3.0.9
    • 2.1.7
    • 1.1.21
    • 5.0.12
    • 3.0.9

    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-407Inefficient Algorithmic Complexity

      Class

      An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.

      Entry at MITRE CWE-407

    References & sources

    • github.comjuliangruber/brace-expansion/security/advisories/GHSA-q2hr-2g5m…x_refsource_CONFIRM
    • github.comjuliangruber/brace-expansion/commit/33a5ef17b8d800bbfa8c52b14c3…x_refsource_MISC
    • github.comjuliangruber/brace-expansion/commit/bdff773f98e5988616b7039cc9b…x_refsource_MISC
    • github.comjuliangruber/brace-expansion/commit/c55e67d8d8b1c56a2474afff15c…x_refsource_MISC
    • github.comjuliangruber/brace-expansion/commit/ffdfa3e3806bed17c0874b8f143…x_refsource_MISC
    • NVD (NIST)vuln/detail/CVE-2026-102277advisory
    • github.comjuliangruber/brace-expansionpackage

    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-2026-102277","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-09-29T19:38:46.678388Z"}

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

    2. ReceivedGitHub

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

      Weakness type: CWE-407, CWE-400

      Description added or changed

      Show 10 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      The brace-expansion library generates arbitrary strings containing a common prefix and suffix. Prior to 1.1.21, 2.1.7, 3.0.9, and 5.0.12, the expand function handles untrusted {a},b}-shaped patterns with many trailing closing braces by restarting its scan once for each trailing closing brace. The successive full-input rescans with linear working-string growth cause quadratic CPU time and memory pressure that can block the Node.js event loop. The process eventually recovers, making the impact a recoverable CPU denial of service. This issue is fixed in versions 1.1.21, 2.1.7, 3.0.9, and 5.0.12.
      CVSSadded
      —
      AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
      Weakness type (CWE)added
      —
      CWE-407
      Weakness type (CWE)added
      —
      CWE-400
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/102xxx/CVE-2026-102277.json">CVE-2026-102277</a>
      Referenceadded
      —
      https://github.com/juliangruber/brace-expansion/commit/33a5ef17b8d800bbfa8c52b14c39043b6aac1a96
      Referenceadded
      —
      https://github.com/juliangruber/brace-expansion/commit/bdff773f98e5988616b7039cc9b508df5d640b22
      Referenceadded
      —
      https://github.com/juliangruber/brace-expansion/commit/c55e67d8d8b1c56a2474afff15c2891166b2d364
      Referenceadded
      —
      https://github.com/juliangruber/brace-expansion/commit/ffdfa3e3806bed17c0874b8f1439b084de354a7e
      Referenceadded
      —
      https://github.com/juliangruber/brace-expansion/security/advisories/GHSA-q2hr-2g5m-vwhr

      Source identifier: security-advisories@github.com

    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-2026-102277
    <a href="https://intel.neosec.eu/en/cve/CVE-2026-102277"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-102277.svg?lang=en" alt="CVE-2026-102277 – NEOSEC Intel" height="20"></a>