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CVE-2026-49265ModerateNetworkRevised 7 Nov

OAuthLib: Timing Attack Vulnerability in PKCE code_verifier Comparison

MSRC advisory NVD CVE.org

Assessment

Severity
Moderate
CVSS base score
6.8
Impact
Not stated
Exploitation detected
Unknown: not stated by MSRC
Exploitability
Not assessed
Publicly disclosed
Unknown: not stated by MSRC
EPSS · 30-day forecast
No EPSS score collected
Customer action
Required: follow the MSRC remediation guidance
More details
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
Public detection template
No Nuclei template is listed in the current collected catalog
Component
Mariner
Weakness
CWE-208: Observable Timing Discrepancy
Issued by
GitHub_M
Published
15 Oct 2026 · October 2026
Last revised
7 Nov 2026Information published.
CVSS 3.1 base metricsRed raises the risk · green lowers it
Attack vector
NetworkAV:N
Attack complexity
HighAC:H
Privileges required
NonePR:N
User interaction
RequiredUI:R
Scope
UnchangedS:U
Confidentiality
HighC:H
Integrity
HighI:H
Availability
NoneA:N

Updates that fix it

0 KBs

No KB listed

No KB update is listed in the collected MSRC record. Check the MSRC advisory for product releases and other remedies.

Affected products

Open Source Software
2 affected products
  • azl3 python-oauthlib 3.2.2-3 on Azure Linux 3.0
  • azl3 python-oauthlib 3.2.2-4 on Azure Linux 3.0

What changed

  1. Detection template: Unknown: detection-template evidence is incomplete or retained → No Nuclei template listed
  2. Detection template: No Nuclei template listed → Unknown: detection-template evidence is incomplete or retained
  3. Detection template: Unknown: detection-template evidence is incomplete or retained → No Nuclei template listed
  4. Detection template: No Nuclei template listed → Unknown: detection-template evidence is incomplete or retained
  5. Affected products: azl3 python-oauthlib 3.2.2-3 on Azure Linux 3.0 → azl3 python-oauthlib 3.2.2-3 on Azure Linux 3.0, azl3 python-oauthlib 3.2.2-4 on Azure Linux 3.0
  6. Detection template: No Nuclei template listed · Customer action: Required: apply the update → Required: follow the MSRC remediation guidance · Public disclosure: No → Unknown: not stated by MSRC · Exploitation detected: Not reported by MSRC → Unknown: not stated by MSRC
  7. Affected products: azl3 httpd 2.4.68-1 on Azure Linux 3.0 → azl3 python-oauthlib 3.2.2-3 on Azure Linux 3.0
  8. Detection template: Unknown: exploit-code evidence is incomplete or retained → No Nuclei template listed · CISA KEV: Unknown: catalog evidence is incomplete or retained → Not listed in the collected catalog
  9. Detection template: No Nuclei template listed → Unknown: exploit-code evidence is incomplete or retained · CISA KEV: Not listed in the collected catalog → Unknown: catalog evidence is incomplete or retained
Page history

Changes are dated when recorded; day views use the last saved version from that UTC day, and citations stay fixed.

Cite this version
Field-level log (39)

Up to 100 recent field edits are shown; older edits may be outside retention.

  1. 7 Nov 2026 · 08:59:22 UTC Last revised1 Nov 2026 14:46 UTC → 7 Nov 2026 01:48 UTC
  2. 6 Nov 2026 · 17:32:22 UTC Public detection templateUnknown: detection-template evidence is incomplete or retained → No Nuclei template listed
  3. 6 Nov 2026 · 17:32:22 UTC Source coverage: public-exploit-codeIncomplete → Current
  4. 6 Nov 2026 · 17:32:22 UTC Source coverage: first-epssIncomplete → Current
  5. 6 Nov 2026 · 17:32:22 UTC Source coverage: msrc-cvrfIncomplete → Current
  6. 6 Nov 2026 · 16:31:02 UTC Public detection templateNo Nuclei template listed → Unknown: detection-template evidence is incomplete or retained
  7. 6 Nov 2026 · 16:31:02 UTC Source coverage: public-exploit-codeCurrent → Incomplete
  8. 6 Nov 2026 · 16:31:02 UTC Source coverage: first-epssCurrent → Incomplete
  9. 6 Nov 2026 · 16:31:02 UTC Source coverage: msrc-cvrfCurrent → Incomplete
  10. 2 Nov 2026 · 17:30:39 UTC Public detection templateUnknown: detection-template evidence is incomplete or retained → No Nuclei template listed
  11. 2 Nov 2026 · 17:30:39 UTC Source coverage: public-exploit-codeIncomplete → Current
  12. 2 Nov 2026 · 17:30:39 UTC Source coverage: first-epssIncomplete → Current
  13. 2 Nov 2026 · 17:30:39 UTC Source coverage: msrc-cvrfIncomplete → Current
  14. 2 Nov 2026 · 16:27:39 UTC Public detection templateNo Nuclei template listed → Unknown: detection-template evidence is incomplete or retained
  15. 2 Nov 2026 · 16:27:39 UTC Source coverage: public-exploit-codeCurrent → Incomplete
  16. 2 Nov 2026 · 16:27:39 UTC Source coverage: first-epssCurrent → Incomplete
  17. 2 Nov 2026 · 16:27:39 UTC Source coverage: msrc-cvrfCurrent → Incomplete
  18. 2 Nov 2026 · 09:04:36 UTC Last revised24 Oct 2026 14:48 UTC → 1 Nov 2026 14:46 UTC
  19. 2 Nov 2026 · 09:04:36 UTC Affected productsazl3 python-oauthlib 3.2.2-3 on Azure Linux 3.0 → azl3 python-oauthlib 3.2.2-3 on Azure Linux 3.0, azl3 python-oauthlib 3.2.2-4 on Azure Linux 3.0
  20. 29 Oct 2026 · 20:19:26 UTC Public detection templateNo Nuclei template listed
  21. 29 Oct 2026 · 20:19:26 UTC EPSSNot scored → No EPSS score collected
  22. 29 Oct 2026 · 20:19:26 UTC Customer actionRequired: apply the update → Required: follow the MSRC remediation guidance
  23. 29 Oct 2026 · 20:19:26 UTC Publicly disclosedNo → Unknown: not stated by MSRC
  24. 29 Oct 2026 · 20:19:26 UTC Exploitation detectedNot reported by MSRC → Unknown: not stated by MSRC
  25. 26 Oct 2026 · 07:26:10 UTC Affected productsazl3 httpd 2.4.68-1 on Azure Linux 3.0 → azl3 python-oauthlib 3.2.2-3 on Azure Linux 3.0
  26. 25 Oct 2026 · 07:41:18 UTC Last revised15 Oct 2026 01:10 UTC → 24 Oct 2026 14:48 UTC
  27. 23 Oct 2026 · 09:33:49 UTC Public exploit codeUnknown: exploit-code evidence is incomplete or retained → No Nuclei template listed
  28. 23 Oct 2026 · 09:33:49 UTC CISA KEVUnknown: catalog evidence is incomplete or retained → Not listed in the collected catalog
  29. 23 Oct 2026 · 09:33:49 UTC Source coverage: public-exploit-codeIncomplete → Current
  30. 23 Oct 2026 · 09:33:49 UTC Source coverage: first-epssIncomplete → Current
  31. 23 Oct 2026 · 09:33:49 UTC Source coverage: cisa-kevIncomplete → Current
  32. 23 Oct 2026 · 09:33:49 UTC Source coverage: msrc-cvrfIncomplete → Current
  33. 23 Oct 2026 · 08:31:50 UTC Public exploit codeNo Nuclei template listed → Unknown: exploit-code evidence is incomplete or retained
  34. 23 Oct 2026 · 08:31:50 UTC CISA KEVNot listed in the collected catalog → Unknown: catalog evidence is incomplete or retained
  35. 23 Oct 2026 · 08:31:50 UTC Source coverage: public-exploit-codeCurrent → Incomplete
  36. 23 Oct 2026 · 08:31:50 UTC Source coverage: first-epssCurrent → Incomplete
  37. 23 Oct 2026 · 08:31:50 UTC Source coverage: cisa-kevCurrent → Incomplete
  38. 23 Oct 2026 · 08:31:50 UTC Source coverage: msrc-cvrfCurrent → Incomplete
  39. 18 Oct 2026 · 14:54:30 UTC Link: October 2026/security?release=2026-Oct#cves

Explore global source statements, affected packages and advisory history for CVE-2026-49265. The catalog has a separate collection scope from Microsoft release records.

Collected exploitation and prediction evidence

Risk source coverage

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

cve-program · CVE-2026-49265

Published

OAuthLib: Timing Attack Vulnerability in PKCE code_verifier Comparison

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.

Source published
13 Oct 2026 15:47:11 UTC
Source modified
13 Oct 2026 16:19:39 UTC
Observed here
23 Oct 2026 15:48:27 UTC
Source terms
CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · 6.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N

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