CVE-2015-2951: JWT.php in F21 JWT before 2.0 allows remote attackers to bypass signature verification via crafted tokens.

Q: How do I fix CVE-2015-2951?

jwt: upgrade to newer than 1.0. Exact commands for each OS are on this page.

Q: Is CVE-2015-2951 being exploited?

CVE-2015-2951 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-2015-2951 affect?

CVE-2015-2951 affects jwt. Severity is medium (CVSS 5.0). JWT.php in F21 JWT before 2.0 allows remote attackers to bypass signature verification via crafted tokens.

Q: How urgent is CVE-2015-2951?

Priority 40/100. No elevated risk signals yet.

This month

MEDIUM 5.0UPGRADE

CVE-2015-2951 is a medium-severity flaw (CVSS 5.0) affecting jwt. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

JWT.php in F21 JWT before 2.0 allows remote attackers to bypass signature verification via crafted tokens.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	3.7% (top 10%)
CISA exploited list	No
Weakness	CWE-20
Published	2015-06-05
Last modified	2026-06-17

Publisher (CNA): JPCERT/CC · Vendor: f21

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2015-06-05 10:59 UTCPublished CVE record published
2026-06-17 00:25 UTCUpdated Record last modified

f21 jwt UPGRADE

Affected: <= 1.0

Fixed in: newer than 1.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy jwt || rpm -q jwt || jwt --version

2. UPGRADE to newer than 1.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade jwt

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade jwt

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2015-2951?

jwt: upgrade to newer than 1.0. Exact commands for each OS are on this page.

Is CVE-2015-2951 being exploited?

CVE-2015-2951 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-2015-2951 affect?

CVE-2015-2951 affects jwt. Severity is medium (CVSS 5.0). JWT.php in F21 JWT before 2.0 allows remote attackers to bypass signature verification via crafted tokens.

How urgent is CVE-2015-2951?

Priority 40/100. No elevated risk signals yet.

Software pages

PHP vulnerabilities

Related CVEs

CVE-2025-45770 HIGH 7.0 UPGRADE jwt v5.4.3 was discovered to contain weak encryption
CVE-2021-41106 MEDIUM 4.4 UPGRADE JWT is a library to work with JSON Web Token and JSON Web Signature
CVE-2016-7037 HIGH 7.5 UPGRADE The verify function in Encryption/Symmetric.php in Malcolm Fell jwt before 1.0.3 does not use a timing-safe fu

References

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