CVE-2025-65015
Description
joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. In versions from 1.3.3 to before 1.3.5 and from 1.4.0 to before 1.4.2, the ExceededSizeError exception messages are embedded with non-decoded JWT token parts and may cause Python logging to record an arbitrarily large, forged JWT payload. In situations where a misconfigured — or entirely absent — production-grade web server sits in front of a Python web application, an attacker may be able to send arbitrarily large bearer tokens in the HTTP request headers. When this occurs, Python logging or diagnostic tools (e.g., Sentry) may end up processing extremely large log messages containing the full JWT header during the joserfc.jwt.decode() operation. The same behavior also appears when validating claims and signature payload sizes, as the library raises joserfc.errors.ExceededSizeError() with the full payload embedded in the exception message. Since the payload is already fully loaded into memory at this stage, the library cannot prevent or reject it. This issue has been patched in versions 1.3.5 and 1.4.2.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
Mitigation details
CVE-2025-65015 NameCVE-2025-65015 Descriptionjoserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. In versions from 1.3.3 to before 1.3.5 and from 1.4.0 to before 1.4.2, the ExceededSizeError exception messages are embedded with non-decoded JWT token parts and may cause Python logging to record an arbitrarily large, forged JWT…
CVE-2025-65015
| Name | CVE-2025-65015 |
| Description | joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. In versions from 1.3.3 to before 1.3.5 and from 1.4.0 to before 1.4.2, the ExceededSizeError exception messages are embedded with non-decoded JWT token parts and may cause Python logging to record an arbitrarily large, forged JWT payload. In situations where a misconfigured — or entirely absent — production-grade web server sits in front of a Python web application, an attacker may be able to send arbitrarily large bearer tokens in the HTTP request headers. When this occurs, Python logging or diagnostic tools (e.g., Sentry) may end up processing extremely large log messages containing the full JWT header during the joserfc.jwt.decode() operation. The same behavior also appears when validating claims and signature payload sizes, as the library raises joserfc.errors.ExceededSizeError() with the full payload embedded in the exception message. Since the payload is already fully loaded into memory at this stage, the library cannot prevent or reject it. This issue has been patched in versions 1.3.5 and 1.4.2. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
Vulnerable and fixed packages
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| joserfc (PTS) | trixie | 1.1.0-1 | fixed |
| forky, sid | 1.6.8-1 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| joserfc | source | trixie | (not affected) | |||
| joserfc | source | (unstable) | 1.4.3-1 |
Notes
[trixie] - joserfc <not-affected> (Vulnerable code not present)
https://github.com/authlib/joserfc/security/advisories/GHSA-frfh-8v73-gjg4
Fixed by: https://github.com/authlib/joserfc/commit/63932f169d924caffafa761af2122b82059017f7 (1.4.2)
Fixed by: https://github.com/authlib/joserfc/commit/673c8743fd0605b0e1de6452be6cba75f44e466b (1.3.5)
Introduced in: https://github.com/authlib/joserfc/commit/62d968b019ff0b9d4ad2ad04864d311cb826f5ca (1.3.4)
Apply commands
[trixie] - joserfc <not-affected> (Vulnerable code not present)https://github.com/authlib/joserfc/security/advisories/GHSA-frfh-8v73-gjg4Fixed by: https://github.com/authlib/joserfc/commit/63932f169d924caffafa761af2122b82059017f7 (1.4.2)Fixed by: https://github.com/authlib/joserfc/commit/673c8743fd0605b0e1de6452be6cba75f44e466b (1.3.5)Introduced in: https://github.com/authlib/joserfc/commit/62d968b019ff0b9d4ad2ad04864d311cb826f5ca (1.3.4)OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| debian | forky | fixed | 1.4.3-1 |
| debian | sid | fixed | 1.4.3-1 |
| debian | trixie | fixed | 0 |
References
- https://github.com/authlib/joserfc/security/advisories/GHSA-frfh-8v73-gjg4
- https://nvd.nist.gov/vuln/detail/CVE-2025-65015
- https://github.com/authlib/joserfc/commit/63932f169d924caffafa761af2122b82059017f7
- https://github.com/authlib/joserfc/commit/673c8743fd0605b0e1de6452be6cba75f44e466b
- https://github.com/authlib/joserfc
- https://github.com/authlib/joserfc/releases/tag/1.3.5
- https://github.com/authlib/joserfc/releases/tag/1.4.2
- https://security-tracker.debian.org/tracker/CVE-2025-65015
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.