MediumCVE-2026-0864

    Configuration Injection via Carriage Return (\r) in write() method (CVE-2026-0864)

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

    What is affected, what to do

    When using the "configparser" module to write configuration files containing multi-line text values with carriage return characters (\r) the resulting file could be injected with unexpected keys and values if the attacker controls the written value.

    Update Python Software Foundation CPython to version 3.10.21, Python Software Foundation CPython to version 3.11.16, Python Software Foundation CPython to version 3.12.14.

    Affected
    • Python Software Foundation CPython lt *..3.10.21
    • Python Software Foundation CPython lt 3.11.0..3.11.16
    • Python Software Foundation CPython lt 3.12.0..3.12.14
    • Python Software Foundation CPython lt 3.13.0..3.13.15
    • Python Software Foundation CPython lt 3.14.0..3.14.7
    • Python Software Foundation CPython lt 3.15.0a1..3.15.0b4
    Fixed in
    • Python Software Foundation CPython 3.10.21
    • Python Software Foundation CPython 3.11.16
    • Python Software Foundation CPython 3.12.14
    • Python Software Foundation CPython 3.13.15
    • Python Software Foundation CPython 3.14.7
    • Python Software Foundation CPython 3.15.0b4

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

    Metrics

    5.5

    Priority

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

    Source: NVD, CVSS v3

    5.5

    CVSS v3

    Severity Medium on the scale from 0 to 10.

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

    0.1 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 2.3

    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
    47.06 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
    5.5 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
    5.5
    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
    4.1
    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
    0.1 %
    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
    2.3
    Low — this CVE sits in the lower 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
    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-74

    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

    When using the "configparser" module to write configuration files containing multi-line text values with carriage return characters (\r) the resulting file could be injected with unexpected keys and values if the attacker controls the written value.

    Source: suse_csaf, BSI WID Portal, BSI CSAF, OSV (Open Source Vulnerabilities), Microsoft Security Update Guide, cvelistv5, NVD (NIST), CVE.org (MITRE)

    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
    Python Software FoundationCPython
    • 3.12.0 – < 3.12.14
    • 3.11.0 – < 3.11.16
    • 3.13.0 – < 3.13.15
    • < 3.10.21
    • 3.15.0a1 – < 3.15.0b4
    • 3.14.0 – < 3.14.7
    • 3.12.14
    • 3.11.16
    • 3.13.15
    • 3.10.21
    • 3.15.0b4
    • 3.14.7
    pythonpython
    • < 3.10.21
    • 3.11.0 – < 3.11.16
    • 3.15.0
    • 3.14.0 – < 3.14.7
    • 3.13.0 – < 3.13.15
    • 3.12.0 – < 3.12.14
    • 3.10.21
    • 3.11.16
    • —
    • 3.14.7
    • 3.13.15
    • 3.12.14
    Open SourcePython CPython
    • < 3.15.0
    • 3.15.0
    Distribution and container packages (4)

    Downstream packages (e.g. Bitnami, Debian, Ubuntu, Red Hat). Versions refer to the distribution, not the vendor.

    Distribution and container packages
    Affected versionsFixed in
    bitnamipython-min
    • 3.13.0
    • 3.12.0
    • 3.14.0
    • 3.11.0
    • —
    • —
    • —
    • —

    Vendors and products

    Weakness classes (CWE)

    • CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

      Class

      The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.

      Entry at MITRE CWE-74

    References & sources

    • github.compython/cpython/pull/151559web, Patch, Issue tracking, Patch
    • mail.python.orgarchives/list/security-announce@python.org/thread/CV4NE6AFCRJL7…advisory, Vendor advisory, Mailing list, Vendor advisory
    • github.compython/cpython/issues/143927report, Issue tracking, Issue tracking, Patch
    • github.compython/cpython/commit/5858e42c539dac8394636a6e9b30472b8994851ffix, Patch, Patch
    • github.compython/cpython/commit/0adb386f6e68eb2e73d32e19f235d012df009528fix, Patch, Patch
    • github.compython/cpython/commit/71f2e02a52d47417a6fd69f456346cd8aa7aca98fix, Patch, Patch
    • github.compython/cpython/commit/aaf850fd333cd89e9aada03d92aaa788a6cb1bb8fix, Patch, Patch
    • github.compython/cpython/commit/db4a157c790479710a1a840d7937c5c815a6f8b6Patch, Patch
    • github.compython/cpython/commit/12dcbd74d3563016a8cb8c47e4898889f34f74ddfix, Patch, Patch
    • github.compython/cpython/commit/274de100bbf4345bd0c23ef5b446722e9e636908fix, Patch, Patch
    • NVD (NIST)vuln/detail/CVE-2026-0864web

    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 modifiedpython.org

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://github.com/python/cpython/commit/12dcbd74d3563016a8cb8c47e4898889f34f74dd
      Referenceadded
      —
      https://github.com/python/cpython/commit/274de100bbf4345bd0c23ef5b446722e9e636908

      Source identifier: cna@python.org

    2. Record modifiedpython.org

      1 individual change: Affected versions (publisher)

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)changed
      CPython
      CPython

      Source identifier: cna@python.org

    3. Record modifiedpython.org

      Show 3 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://github.com/python/cpython/commit/0adb386f6e68eb2e73d32e19f235d012df009528
      Referenceadded
      —
      https://github.com/python/cpython/commit/71f2e02a52d47417a6fd69f456346cd8aa7aca98
      Referenceadded
      —
      https://github.com/python/cpython/commit/aaf850fd333cd89e9aada03d92aaa788a6cb1bb8

      Source identifier: cna@python.org

    4. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: none known, automatable: no

      Weakness type: CWE-74

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Weakness type (CWE)added
      —
      CWE-74
      SSVC assessmentadded
      —
      {"id":"CVE-2026-0864","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-06-23T18:34:23.504725Z"}

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

    5. Receivedpython.org

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

      Description added or changed

      Show 7 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      CPython
      Descriptionadded
      —
      When using the "configparser" module to write configuration files containing multi-line text values with carriage return characters (\r) the resulting file could be injected with unexpected keys and values if the attacker controls the written value.
      CVSSadded
      —
      AV:L/AC:L/AT:P/PR:H/UI:P/VC:N/VI:H/VA:N/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
      Referenceadded
      —
      https://github.com/python/cpython/commit/5858e42c539dac8394636a6e9b30472b8994851f
      Referenceadded
      —
      https://github.com/python/cpython/issues/143927
      Referenceadded
      —
      https://github.com/python/cpython/pull/151559
      Referenceadded
      —
      https://mail.python.org/archives/list/security-announce@python.org/thread/CV4NE6AFCRJL7XQOHX7J5TSDHUWVWGJS/

      Source identifier: cna@python.org

    One NVD translation into another language is hidden.

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