CVE-2026-35041: fast-jwt provides fast JSON Web Token (JWT) implementation

Q: How do I fix CVE-2026-35041?

fast-jwt: upgrade to 6.2.1. Exact commands for each OS are on this page.

Q: Is CVE-2026-35041 being exploited?

CVE-2026-35041 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-2026-35041 affect?

CVE-2026-35041 affects fast-jwt. Severity is medium (CVSS 4.2). fast-jwt provides fast JSON Web Token (JWT) implementation. From 5.0.0 to 6.2.0, a denial-of-service condition exists in fast-jwt when the allowedAud verification option is configured using a regular expression. Because the aud claim is att

Q: How urgent is CVE-2026-35041?

Priority 24/100. Public exploit reference

Routine

MEDIUM 4.2UPGRADE

CVE-2026-35041 is a medium-severity flaw (CVSS 4.2) affecting fast-jwt. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

fast-jwt provides fast JSON Web Token (JWT) implementation. From 5.0.0 to 6.2.0, a denial-of-service condition exists in fast-jwt when the allowedAud verification option is configured using a regular expression. Because the aud claim is attacker-controlled and the library evaluates it against the supplied RegExp, a crafted JWT can trigger catastrophic backtracking in the JavaScript regex engine, resulting in significant CPU consumption during ver

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	4.2 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	High
User interaction	Required
EPSS exploit chance	0.3% (top 82%)
CISA exploited list	No
Weakness	CWE-1333
Published	2026-04-09
Last modified	2026-10-26

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

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-09 16:16 UTCPublished CVE record published
2026-10-26 22:10 UTCUpdated Record last modified

nearform fast-jwt UPGRADE

Affected: >= 5.0.0 and < 6.2.1

Fixed in: 6.2.1

Safe to downgrade to: a release before 5.0.0

1. Check installed version

npm ls fast-jwt

2. UPGRADE to 6.2.1

npm install fast-jwt@">=6.2.1"

3. If no update is available yet, DOWNGRADE to a release before 5.0.0

npm view fast-jwt versions npm install fast-jwt@"<5.0.0"

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-2026-35041?

fast-jwt: upgrade to 6.2.1. Exact commands for each OS are on this page.

Is CVE-2026-35041 being exploited?

CVE-2026-35041 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-2026-35041 affect?

CVE-2026-35041 affects fast-jwt. Severity is medium (CVSS 4.2). fast-jwt provides fast JSON Web Token (JWT) implementation. From 5.0.0 to 6.2.0, a denial-of-service condition exists in fast-jwt when the allowedAud verification option is configured using a regular expression. Because the aud claim is att

How urgent is CVE-2026-35041?

Priority 24/100. Public exploit reference

Related CVEs

CVE-2026-34950 CRITICAL 9.1 UPGRADE fast-jwt provides fast JSON Web Token (JWT) implementation
CVE-2026-35040 MEDIUM 5.3 UPGRADE fast-jwt provides fast JSON Web Token (JWT) implementation
CVE-2026-35042 HIGH 7.5 UPGRADE fast-jwt provides fast JSON Web Token (JWT) implementation
CVE-2026-35039 CRITICAL 9.1 UPGRADE fast-jwt provides fast JSON Web Token (JWT) implementation

References

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