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No exploitation reportedFix available

CVE-2026-49265

No exploitation reported by the sources we read.

  • Published2026-10-13
  • Fixed in4.0.0
  • WeaknessCWE-208

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

OAuthLib is an implementation of the OAuth request-signing logic for Python 3.6+. From 3.0.0 until 4.0.0, OAuthLib's PKCE checks in oauthlib/oauth2/rfc6749/grant_types/authorization_code.py compare attacker-supplied code_verifier values with stored challenges using ordinary string equality in code_challenge_method_plain and code_challenge_method_s256. Because the comparison can return after a length difference or the first mismatching character, repeated token endpoint measurements can reveal common-prefix timing information that could potentially allow recovery of the code_verifier, unauthorized access-token acquisition, and account takeover. Practical exploitation requires an intercepted, single-use authorization code and enough measurements to overcome real-world network noise; the local timing benchmark does not establish practical remote account takeover, so the weakness remains a defense-in-depth concern. This issue is fixed in version 4.0.0.

Timeline

dates in UTC
  1. 2026-10-1316:17CVE publishedNVD

Versions per branch

OSV
oauthlib
BranchAffectedFixed in
4.0≥ 3.0.0, < 4.0.04.0.0

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As GitHub_M, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • oauthlib
    Affected
    • = >= 3.0.0, < 4.0.0no fix stated

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-10-13

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • airflow-2MinimOSall versions · no fixed version listedand 13 other packages
  • airflow-3CleanStartall versions · fixed in 3.0.6-r9
  • airflow-3CleanStartall versions · fixed in 3.1.8-r13
  • airflow-3CleanStartall versions · fixed in 3.2.1-r11
  • airflow-3CleanStartall versions · fixed in 3.2.2-r8
  • airflow-3CleanStartall versions · fixed in 3.3.2-r1
  • ansible-operatorChainguardall versions · fixed in 1.42.3-r18
  • ansible-operator-fipsChainguardall versions · fixed in 1.42.3-r15

109 more package ranges on OSV.dev

Vendor advisories

  • CVE-2026-49265 Red Hat Product Security9 products fixed · 233 known affected

    oauthlib: oauthlib: Timing attack vulnerability in PKCE code_verifier/code_challenge comparison allows authorization code recovery

    openshift-sandboxed-containers/osc-podvm-builder-rhel9 as a component of Confidential Compute Attestation · workload-availability/fence-agents-remediation-rhel9-operator as a component of Fence Agents Remediation Operator · lightspeed-core/lightspeed-stack-rhel9 as a component of Lightspeed Core · +230 more

  • RHSA-2026:92452 Red Hat Product Security5 products fixed

    Red Hat Security Advisory: Red Hat Enterprise Linux AI 3.5.2 enhancement update

  • RHSA-2026:92449 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Red Hat Enterprise Linux AI 3.5.2 enhancement update

  • RHSA-2026:82415 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Red Hat AI Inference 3.5.2 (cpu)

  • RHSA-2026:82368 Red Hat Product Security2 products fixed

    Red Hat Security Advisory: Red Hat AI Inference 3.5.2 (cuda)

Full record on NVD

Fix

  1. Update oauthlib to 4.0.0
  2. Vendor fix Red Hat Product Security RHSA-2026:92452 · 5 productsThe container images provided by this update can be downloaded from the Red Hat container registry at registry.redhat.io using the "podman pull" command. For details on deploying and configuring RHEL AI, see the Red Hat Enterprise Linux AI documentation at https://docs.redhat.com/en/documentation/…
  3. Vendor fix Red Hat Product Security RHSA-2026:92449 · 1 productThe container disk images provided by this update can be downloaded from the Red Hat container registry at registry.redhat.io using the "podman pull" command, for use with OpenShift Virtualization. For details on deploying and configuring RHEL AI, see the Red Hat Enterprise Linux AI documentation …
  4. Vendor fix Red Hat Product Security RHSA-2026:82415 · 1 productFor more information visit https://access.redhat.com/errata/RHSA-2026:82415
  5. Vendor fix Red Hat Product Security RHSA-2026:82368 · 2 productsFor more information visit https://access.redhat.com/errata/RHSA-2026:82368
  6. Workaround from the vendor Red Hat Product Security RHSA-2026:92452 · 7 productsMitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
  7. No fix available, says the vendor Red Hat Product Security CVE-2026-49265 · 233 productsFix deferred

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

  • NVDCVE recordread 2026-10-23
  • CISA-ADPSSVC decisionnone2026-10-13
  • CNACVSS 3.16.8known since 2026-10-23
  • CNAweakness (CWE)CWE-208known since 2026-10-23
  • FIRST EPSSEPSS score0.2 %2026-11-05
  • OSVaffected packages—
  • GitHub AdvisoriesadvisoryMODERATE2026-09-29

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
Published
2026-10-13
Last Modified
2026-10-16
NVD status
Deferred
GitHub Advisory
GHSA-xpv3-w29h-x7cv

Frequently asked questions

What is CVE-2026-49265?

OAuthLib is an implementation of the OAuth request-signing logic for Python 3.6+. From 3.0.0 until 4.0.0, OAuthLib's PKCE checks in oauthlib/oauth2/rfc6749/grant_types/authorization_code.py compare attacker-supplied code_verifier values with stored challenges using ordinary string equality in code_challenge_method_plain and code_challenge_method_s256. Because the comparison can return after a length difference or the first mismatching character, repeated token endpoint measurements can reveal common-prefix timing information that could potentially allow recovery of the code_verifier, unauthorized access-token acquisition, and account takeover. Practical exploitation requires an intercepted, single-use authorization code and enough measurements to overcome real-world network noise; the local timing benchmark does not establish practical remote account takeover, so the weakness remains a defense-in-depth concern. This issue is fixed in version 4.0.0.

Is CVE-2026-49265 actively exploited?

Active exploitation of CVE-2026-49265 has not been confirmed. Its EPSS score was 0.2% on 2026-11-05, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-49265?

CVE-2026-49265 has a CVSS v3 base score of 6.8 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N.

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