# CVE-2025-65015: joserfc has Possible Uncontrolled Resource Consumption Vulnerability Triggered by Logging Arbitrarily Large JWT Token Payloads

Source: https://junglewise.ai/threats/cve-2025-65015-joserfc-has-possible-uncontrolled-resource-consumption  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-11-18  
License: CC BY 4.0 with a link back

CVE-2025-65015 · Severity: critical · CVSS 7.5 · Published 2025-11-18

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.

Technologies: [joserfc (PyPI)](https://junglewise.ai/threats/technologies/pypi-joserfc). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2025-65015 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-65015 being exploited in the wild.

**How severe is CVE-2025-65015?** Critical severity, with a CVSS score of 7.5, published 18 November 2025.

**Which products and versions are affected?** joserfc (PyPI) >= 1.3.3, < 1.3.5, ECOSYSTEM:introduced=1.3.3,fixed=1.3.5, ECOSYSTEM:introduced=1.3.3,fixed=1.3.5,introduced=1.4.0,fixed=1.4.2.

**Is there a fix for CVE-2025-65015?** Yes. joserfc (PyPI): upgrade to 1.3.5, 1.4.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2025-65015?** Check whether you run Hsiaoming Joserfc or joserfc (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- joserfc (PyPI): upgrade to 1.3.5, 1.4.2 or later

  ```sh
  pip install "joserfc>=1.4.2"
  ```


## Affected products

- Hsiaoming Joserfc
- joserfc (PyPI) >= 1.3.3, < 1.3.5, ECOSYSTEM:introduced=1.3.3,fixed=1.3.5, ECOSYSTEM:introduced=1.3.3,fixed=1.3.5,introduced=1.4.0,fixed=1.4.2

## Identifiers

- CVE-2025-65015
- GHSA-frfh-8v73-gjg4
- PYSEC-2026-361

## Related threats

- [joserfc memory exhaustion in compact JWS deserialization](https://junglewise.ai/threats/cve-2026-119284-joserfc-is-a-python-library-that-provides-an-implementation-of)
- [joserfc JWE denial of service via unlimited recipients](https://junglewise.ai/threats/cve-2026-119283-joserfc-is-a-python-library-that-provides-an-implementation-of)
- [authlib joserfc authentication bypass via empty HMAC key](https://junglewise.ai/threats/cve-2026-49852-authlib-joserfc-authentication-bypass-via-empty-hmac-key)
- [PYSEC-2026-2529 - joserfc's PBES2 p2c Unbounded Iteration Count enables Denial of Service (DoS)](https://junglewise.ai/threats/cve-2026-27932-joserfc-s-pbes2-p2c-unbounded-iteration-count-enables-denial-of)
- [authlib joserfc resource exhaustion via oversized RFC7797 payloads](https://junglewise.ai/threats/cve-2026-48990-authlib-joserfc-resource-exhaustion-via-oversized-rfc7797)