CVE-2026-35039

Q: How do I fix CVE-2026-35039?

Upgrade fast-jwt to 6.1.0 or later.

Q: Is CVE-2026-35039 being actively exploited?

Not that we know of. CVE-2026-35039 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.21% is the estimated probability that it will be exploited in the next 30 days. That is higher than 12% of all scored CVEs.

Q: How severe is CVE-2026-35039?

CVE-2026-35039 has a CVSS v3 base score of 9.1, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

Q: What does CVE-2026-35039 affect?

Published advisories record a fix for fast-jwt (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

CRITICAL

9.1

CVSS v3

NVD

Description

fast-jwt provides fast JSON Web Token (JWT) implementation. From 0.0.1 to before 6.2.0, setting up a custom cacheKeyBuilder method which does not properly create unique keys for different tokens can lead to cache collisions. This could cause tokens to be mis-identified during the verification process leading to valid tokens returning claims from different valid tokens and users being mis-identified as other users based on the wrong token. Version 6.2.0 contains a patch.

CWE-345 CWE-706 CWE-1289

How to fix

Remediation Available

fast-jwtNVD

Affected:>= 0.1.0, < 6.1.0Fixed in:6.1.0CVE-2026-35039derived from NVD

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Exploit Intelligence

0.21%probability of exploitation in 30 days

12thpercentile

Low risk: more likely to be exploited than 12% of all known CVEs.

References

Patch1

github.com

Vendor Advisory1

github.com

Related Vulnerabilities

Other CWE-345 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-38831	High	7.8	98%	KEV + Ransom	Fix
CVE-2016-4553	High	8.6	80%	-	Fix
CVE-2016-4554	High	8.6	39%	-	Fix
CVE-2023-35719	Medium	6.8	26%	-	-
CVE-2022-26871	Critical	9.8	20%	KEV	-
CVE-2014-4936	High	9.3	17%	-	-

Common questions

How do I fix CVE-2026-35039?

Upgrade fast-jwt to 6.1.0 or later.

Is CVE-2026-35039 being actively exploited?

Not that we know of. CVE-2026-35039 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.21% is the estimated probability that it will be exploited in the next 30 days. That is higher than 12% of all scored CVEs.

How severe is CVE-2026-35039?

CVE-2026-35039 has a CVSS v3 base score of 9.1, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-35039 affect?

Published advisories record a fix for fast-jwt (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

Embed a live status badge for CVE-2026-35039

Markdown

[![CVE-2026-35039](https://tridentstack.com/cve/badge/CVE-2026-35039.svg)](https://tridentstack.com/cve/CVE-2026-35039)

HTML

<a href="https://tridentstack.com/cve/CVE-2026-35039"><img src="https://tridentstack.com/cve/badge/CVE-2026-35039.svg" alt="CVE-2026-35039"></a>

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

See how it works Start freeThis CVE lookup is free and always will be.

This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-22.