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CVE-2026-114617VulnerabilityPublished Updated

Python authlib: Prior to 1.9.0, OpenIDMixin.parse_id_token() reads the nonce_supported decision from the untrusted ID

Affects python-authlibSource GCVE Database

0
Authoritative record:CVE-2026-114617· Medium 4.2

Not known to be exploited · CVSS 4.2 Medium · fixed in 1.9.0 : update python-authlib when convenient.

Data as of 28 Oct 2026, 22:31 UTC

CVSS 3.1 base score
4.2Medium
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 1.9.0
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 22 Oct 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 26.10python-authlibpkg:deb/ubuntu/python-authlib?arch=source&distro=stonkingOther threatsAffected
  • =1.6.7-1
  • =1.7.2-1
  • =1.7.2-2
Fixed in–
Ubuntu Pro 26.04 LTSpython-authlibpkg:deb/ubuntu/python-authlib?arch=source&distro=esm-apps/resoluteOther threatsAffected
  • 1.6.0-1 – 1.6.7-1ubuntu0.1~esm1
5 affected builds
Fixed in–
Ubuntu Pro 24.04 LTSpython-authlibpkg:deb/ubuntu/python-authlib?arch=source&distro=esm-apps/nobleOther threatsAffected
  • 1.2.1-1 – 1.3.0-1ubuntu0.1~esm2
4 affected builds
Fixed in–
Ubuntu Pro 22.04 LTSpython-authlibpkg:deb/ubuntu/python-authlib?arch=source&distro=esm-apps/jammyOther threatsAffected
  • 0.15.4-1 – 0.15.5-1ubuntu0.1~esm2
4 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.9.0, OpenIDMixin.parse_id_token() reads the nonce_supported decision from the untrusted ID token being validated and sets the expected nonce to null when that claim is the JSON boolean false. In implicit and hybrid relying parties, or applications that directly accept externally supplied ID tokens, an attacker with a captured validly signed token can bypass the nonce-to-session binding and replay the victim's token into an attacker-controlled session. Plain authorization code flow is not affected, and the token must still pass signature, issuer, and audience validation. OpenIDMixin.parse_id_token() trusts nonce_supported in both authlib/integrations/base_client/sync_openid.py and authlib/integrations/base_client/async_openid.py to disable the expected nonce. This issue is fixed in version 1.9.0.

References

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