CVE-2025-65015: joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOS

Q: How do I fix CVE-2025-65015?

joserfc: upgrade to 1.3.5, 1.4.2. Exact commands for each OS are on this page.

Q: Is CVE-2025-65015 being exploited?

CVE-2025-65015 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2025-65015 affect?

CVE-2025-65015 affects joserfc. Severity is high (CVSS 7.5). 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

Q: How urgent is CVE-2025-65015?

Priority 46/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

HIGH 7.5REMOTEUPGRADE

CVE-2025-65015 is a high-severity flaw (CVSS 7.5) affecting joserfc. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 62%)
CISA exploited list	No
Weakness	CWE-770
Published	2025-11-18
Last modified	2026-10-18

Publisher (CNA): GitHub, Inc. · Vendor: hsiaoming

Last updated 2026-10-18 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-11-18 23:15 UTCPublished CVE record published
2026-10-18 20:10 UTCUpdated Record last modified

hsiaoming joserfc UPGRADE

Affected: >= 1.3.3 and < 1.3.5 · >= 1.4.0 and < 1.4.2

Fixed in: 1.3.5, 1.4.2

Safe to downgrade to: a release before 1.3.3

1. Check installed version

pip show joserfc

2. UPGRADE to 1.3.5

pip install --upgrade "joserfc>=1.3.5"

3. If no update is available yet, DOWNGRADE to a release before 1.3.3

pip index versions joserfc pip install "joserfc<1.3.3"

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-65015?

joserfc: upgrade to 1.3.5, 1.4.2. Exact commands for each OS are on this page.

Is CVE-2025-65015 being exploited?

CVE-2025-65015 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-65015 affect?

CVE-2025-65015 affects joserfc. Severity is high (CVSS 7.5). 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

How urgent is CVE-2025-65015?

Priority 46/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

Python vulnerabilities

Related CVEs

CVE-2026-27932 HIGH 7.5 UPGRADE joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOS

References

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