HighCVE-2026-82209

    domain-scoped PSL domain cookie (CVE-2026-82209)

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

    What is affected, what to do

    A flaw was found in libcurl when libpsl support is enabled. A remote attacker could exploit this vulnerability by setting a `Set-Cookie` header with a `Domain` attribute that explicitly matches a public suffix.

    Update Curl to version 8.14.2, Curl to version 8.16.1, Curl to version 8.20.1.

    Affected
    • Curl eq 8.0.0..8.0.0
    • Curl eq 7.88.1..7.88.1
    • Curl lt 7.46.0..8.14.2
    • Curl lt 8.15.0..8.16.1
    • Curl lt 8.17.0..8.20.1
    • Curl lt 8.21.0..8.22.0
    • Curl eq 8.21.0..8.21.0
    • Curl eq 8.20.0..8.20.0
    • Curl eq 8.19.0..8.19.0
    • Curl eq 8.18.0..8.18.0
    • Curl eq 8.17.0..8.17.0
    • Curl eq 8.16.0..8.16.0
    • Curl eq 8.15.0..8.15.0
    • Curl eq 8.14.1..8.14.1
    • Curl eq 8.14.0..8.14.0
    • Curl eq 8.13.0..8.13.0
    • Curl eq 8.12.1..8.12.1
    • Curl eq 8.12.0..8.12.0
    • Curl eq 8.11.1..8.11.1
    • Curl eq 8.11.0..8.11.0
    • Curl eq 8.10.1..8.10.1
    • Curl eq 8.10.0..8.10.0
    • Curl eq 8.9.1..8.9.1
    • Curl eq 8.9.0..8.9.0
    • Curl eq 8.8.0..8.8.0
    • Curl eq 8.7.1..8.7.1
    • Curl eq 8.7.0..8.7.0
    • Curl eq 8.6.0..8.6.0
    • Curl eq 8.5.0..8.5.0
    • Curl eq 8.4.0..8.4.0
    • Curl eq 8.3.0..8.3.0
    • Curl eq 8.2.1..8.2.1
    • Curl eq 8.2.0..8.2.0
    • Curl eq 8.1.2..8.1.2
    • Curl eq 8.1.1..8.1.1
    • Curl eq 8.1.0..8.1.0
    • Curl eq 8.0.1..8.0.1
    • Curl eq 7.88.0..7.88.0
    • Curl eq 7.87.0..7.87.0
    • Curl eq 7.86.0..7.86.0
    • Curl eq 7.85.0..7.85.0
    • Curl eq 7.84.0..7.84.0
    • Curl eq 7.83.1..7.83.1
    • Curl eq 7.83.0..7.83.0
    • Curl eq 7.82.0..7.82.0
    • Curl eq 7.81.0..7.81.0
    • Curl eq 7.80.0..7.80.0
    • Curl eq 7.79.1..7.79.1
    • Curl eq 7.79.0..7.79.0
    • Curl eq 7.78.0..7.78.0
    • Curl eq 7.77.0..7.77.0
    • Curl eq 7.76.1..7.76.1
    • Curl eq 7.76.0..7.76.0
    • Curl eq 7.75.0..7.75.0
    • Curl eq 7.74.0..7.74.0
    • Curl eq 7.73.0..7.73.0
    • Curl eq 7.72.0..7.72.0
    • Curl eq 7.71.1..7.71.1
    • Curl eq 7.71.0..7.71.0
    • Curl eq 7.70.0..7.70.0
    • Curl eq 7.69.1..7.69.1
    • Curl eq 7.69.0..7.69.0
    • Curl eq 7.68.0..7.68.0
    • Curl eq 7.67.0..7.67.0
    • Curl eq 7.66.0..7.66.0
    • Curl eq 7.65.3..7.65.3
    • Curl eq 7.65.2..7.65.2
    • Curl eq 7.65.1..7.65.1
    • Curl eq 7.65.0..7.65.0
    • Curl eq 7.64.1..7.64.1
    • Curl eq 7.64.0..7.64.0
    • Curl eq 7.63.0..7.63.0
    • Curl eq 7.62.0..7.62.0
    • Curl eq 7.61.1..7.61.1
    • Curl eq 7.61.0..7.61.0
    • Curl eq 7.60.0..7.60.0
    • Curl eq 7.59.0..7.59.0
    • Curl eq 7.58.0..7.58.0
    • Curl eq 7.57.0..7.57.0
    • Curl eq 7.56.1..7.56.1
    • Curl eq 7.56.0..7.56.0
    • Curl eq 7.55.1..7.55.1
    • Curl eq 7.55.0..7.55.0
    • Curl eq 7.54.1..7.54.1
    • Curl eq 7.54.0..7.54.0
    • Curl eq 7.53.1..7.53.1
    • Curl eq 7.53.0..7.53.0
    • Curl eq 7.52.1..7.52.1
    • Curl eq 7.52.0..7.52.0
    • Curl eq 7.51.0..7.51.0
    • Curl eq 7.50.3..7.50.3
    • Curl eq 7.50.2..7.50.2
    • Curl eq 7.50.1..7.50.1
    • Curl eq 7.50.0..7.50.0
    • Curl eq 7.49.1..7.49.1
    • Curl eq 7.49.0..7.49.0
    • Curl eq 7.48.0..7.48.0
    • Curl eq 7.47.1..7.47.1
    • Curl eq 7.47.0..7.47.0
    • Curl eq 7.46.0..7.46.0
    Fixed in
    • Curl 8.14.2
    • Curl 8.16.1
    • Curl 8.20.1
    • Curl 8.22.0

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

    Metrics

    8.2

    Priority

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

    Source: Vendor (CNA), CVSS v3

    8.2

    CVSS v3

    Severity High on the scale from 0 to 10.

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

    0.4 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 31.3

    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
    74.34 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
    8.2 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
    8.2
    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
    31.3
    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: proof of concept · automatable · Technical impact: partial
    Source: CISA Vulnrichment, as of 8 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-201

    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

    A flaw was found in libcurl when libpsl support is enabled. A remote attacker could exploit this vulnerability by setting a `Set-Cookie` header with a `Domain` attribute that explicitly matches a public suffix. This improper handling causes libcurl to save the cookie with a wildcard domain scope, leading to the cookie being inappropriately sent to arbitrary sibling subdomains under the same public suffix. This could result in sensitive information disclosure.

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

    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
    curlcurl
    • 8.18.0
    • 8.15.0
    • 7.71.1
    • 8.12.1
    • 7.70.0
    • 7.83.0
    • 8.19.0
    • 7.60.0
    • 7.65.1
    • 7.83.1
    • 7.50.3
    • 8.13.0
    • 7.49.1
    • 8.6.0
    • 8.0.0
    • 7.72.0
    • 7.57.0
    • 7.65.3
    • 8.9.0
    • 7.47.1
    • 7.76.1
    • 7.65.0
    • 8.14.1
    • 7.46.0 – < 8.14.2
    • 8.7.0
    • 8.15.0 – < 8.16.1
    • 7.52.0
    • 7.79.0
    • 7.66.0
    • 7.85.0
    • 7.50.0
    • 7.56.1
    • 7.73.0
    • 7.56.0
    • 7.78.0
    • 7.79.1
    • 8.10.1
    • 7.80.0
    • 7.54.1
    • 8.17.0
    • 8.21.0 – < 8.22.0
    • 8.9.1
    • 8.1.1
    • 7.59.0
    • 8.14.0
    • 7.55.0
    • 7.68.0
    • 7.62.0
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • 8.14.2
    • —
    • 8.16.1
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • 8.22.0
    • —
    • —
    • —
    • —
    • —
    • —
    • —

    Vendors and products

    Weakness classes (CWE)

    • CWE-201Insertion of Sensitive Information Into Sent Data

      Base

      The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor.

      Entry at MITRE CWE-201

    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. Record modifiedcurl

      Weakness type: CWE-201

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Weakness type (CWE)added
      —
      CWE-201
      Affected versions (publisher)added
      —
      Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/82xxx/CVE-2026-82209.json">CVE-2026-82209</a>

      Source identifier: 2499f714-1537-4658-8207-48ae4bb9eae9

    2. Initial analysis by NVDNVD

      Newly listed as affected:
      Show 5 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Product configurationadded
      —
      OR *cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:* versions from (including) 7.46.0 up to (excluding) 8.22.0
      Reference typeadded
      —
      curl: https://curl.se/docs/CVE-2026-82209.html Types: Patch, Vendor Advisory
      Reference typeadded
      —
      curl: https://curl.se/docs/CVE-2026-82209.json Types: Vendor Advisory
      Reference typeadded
      —
      CISA-ADP: https://hackerone.com/reports/3972385 Types: Exploit, Mitigation, Third Party Advisory
      Reference typeadded
      —
      curl: https://hackerone.com/reports/3972385 Types: Exploit, Mitigation, Third Party Advisory

      Source identifier: nvd@nist.gov

    3. Record modifiedCISA ADP

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

      CISA assessment (SSVC): exploitation: proof of concept, automatable: yes

      Weakness type: CWE-201

      Show 4 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      CVSSadded
      —
      AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
      Weakness type (CWE)added
      —
      CWE-201
      Referenceadded
      —
      https://hackerone.com/reports/3972385
      SSVC assessmentadded
      —
      {"id":"CVE-2026-82209","role":"CISA Coordinator","options":[{"exploitation":"poc"},{"automatable":"yes"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-09-08T18:47:09.259604Z"}

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

    4. Receivedcurl

      Description added or changed

      Show 5 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      When libpsl support is enabled, libcurl fails to enforce the Public Suffix List boundary check when processing a `Set-Cookie` header where the `Domain` attribute explicitly matches an origin host that is itself a public suffix (e.g., `Domain=co.uk` set by `co.uk`). Instead of coercing it into a strict host-only cookie, libcurl saves the cookie with wildcard domain scope (`.co.uk`). Consequently, the cookie is inappropriately included in subsequent outbound requests or HTTP redirects to arbitrary sibling subdomains under the same public suffix (e.g., `attacker.co.uk`).
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/82xxx/CVE-2026-82209.json">CVE-2026-82209</a>
      Referenceadded
      —
      https://curl.se/docs/CVE-2026-82209.html
      Referenceadded
      —
      https://curl.se/docs/CVE-2026-82209.json
      Referenceadded
      —
      https://hackerone.com/reports/3972385

      Source identifier: 2499f714-1537-4658-8207-48ae4bb9eae9

    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-2026-82209
    <a href="https://intel.neosec.eu/en/cve/CVE-2026-82209"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-82209.svg?lang=en" alt="CVE-2026-82209 – NEOSEC Intel" height="20"></a>