Not ratedCVE-2026-97054

    HTTP/1 server crash due to MaxBytesReader header race in net/http (CVE-2026-97054)

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

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    What is affected, what to do

    For HTTP/1 servers, when MaxBytesReader's limit is exceeded, "Connection: close" header is automatically set without synchronization, which might race with another header being set explicitly in the server handler. As a result, an HTTP/1 server that utilizes MaxBytesReader or MaxBytesHandler can crash due to runtime panic if its handler reads the request body concurrently with writing the response header.

    Update Go standard library Net/http to version 1.26.11, Go standard library Net/http to version 1.27.4.

    Affected
    • Go standard library Net/http lt *..1.26.11
    • Go standard library Net/http lt 1.27.0-0..1.27.4
    Fixed in
    • Go standard library Net/http 1.26.11
    • Go standard library Net/http 1.27.4

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

    Metrics

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    XIEM Effective CVSS

    No value is available for this vulnerability.

    0.0

    CVSS v3

    Severity Not rated on the scale from 0 to 10.

    Source: CVE.org, OSV, EUVD, BSI

    —

    EPSS score

    No value is available for this vulnerability.

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    Severity
    Not rated
    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
    30.00 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
    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
    0.0
    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

    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

    For HTTP/1 servers, when MaxBytesReader's limit is exceeded, "Connection: close" header is automatically set without synchronization, which might race with another header being set explicitly in the server handler. As a result, an HTTP/1 server that utilizes MaxBytesReader or MaxBytesHandler can crash due to runtime panic if its handler reads the request body concurrently with writing the response header.

    Source: cvelistv5, NVD (NIST), OSV (Open Source Vulnerabilities), ENISA EUVD, 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
    Go standard librarynet/http
    • 1.27.0-0 – < 1.27.4
    • < 1.26.11
    • 1.27.4
    • 1.26.11
    GolangGo
    • < 1.27.4
    • < 1.26.11
    • 1.27.4
    • 1.26.11
    gostdlib
    • —
    • 1.27.0-0
    • 1.26.11
    • 1.27.4

    Vendors and products

    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. Receivedgolang.org

      Description added or changed

      Show 6 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      For HTTP/1 servers, when MaxBytesReader's limit is exceeded, "Connection: close" header is automatically set without synchronization, which might race with another header being set explicitly in the server handler. As a result, an HTTP/1 server that utilizes MaxBytesReader or MaxBytesHandler can crash due to runtime panic if its handler reads the request body concurrently with writing the response header.
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/97xxx/CVE-2026-97054.json">CVE-2026-97054</a>
      Referenceadded
      —
      https://go.dev/cl/862185
      Referenceadded
      —
      https://go.dev/issue/82563
      Referenceadded
      —
      https://groups.google.com/g/golang-announce/c/iY8TY0wWgbM
      Referenceadded
      —
      https://pkg.go.dev/vuln/GO-2026-6859

      Source identifier: security@golang.org

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