How severe is CVE-2026-35042?

CVE-2026-35042 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2026-35042 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-35042?

CVE-2026-35042 affects Nearform Fast-jwt. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-35042?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-35042 have an EU (EUVD) identifier?

Yes. CVE-2026-35042 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-19382.

When was CVE-2026-35042 published?

CVE-2026-35042 was published on 2026-04-06 and last updated on 2026-06-17.

CVE-2026-35042

CVE-2026-35042 is a high-severity vulnerability in Nearform Fast-jwt with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-345.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (5th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-19382
Weakness: CWE-345
Affected product: Nearform Fast-jwt
Published: 2026-04-06
Last modified: 2026-06-17

Description

fast-jwt provides fast JSON Web Token (JWT) implementation. In 6.1.0 and earlier, fast-jwt does not validate the crit (Critical) Header Parameter defined in RFC 7515 §4.1.11. When a JWS token contains a crit array listing extensions that fast-jwt does not understand, the library accepts the token instead of rejecting it. This violates the MUST requirement in the RFC.

Frequently asked questions

What is CVE-2026-35042?: fast-jwt provides fast JSON Web Token (JWT) implementation. In 6.1.0 and earlier, fast-jwt does not validate the crit (Critical) Header Parameter defined in RFC 7515 §4.1.11. When a JWS token contains a crit array listing extensions that fast-jwt does not understand, the library accepts the token instead of rejecting it. This violates the MUST requirement in the RFC.
How severe is CVE-2026-35042?: CVE-2026-35042 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2026-35042 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-35042?: CVE-2026-35042 affects Nearform Fast-jwt. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-35042?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-35042 have an EU (EUVD) identifier?: Yes. CVE-2026-35042 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-19382.
When was CVE-2026-35042 published?: CVE-2026-35042 was published on 2026-04-06 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:nearform:fast-jwt:*:*:*:*:*:node.js:*:*

More vulnerabilities in Nearform Fast-jwt

CVE-2026-35039 — Critical (CVSS 9.1): fast-jwt provides fast JSON Web Token (JWT) implementation. From 0.0.1 to before 6.2.0, setting up a custom…
CVE-2026-34950 — Critical (CVSS 9.1): fast-jwt provides fast JSON Web Token (JWT) implementation. In 6.1.0 and earlier, the publicKeyPemMatcher regex in…
CVE-2023-48223 — Medium (CVSS 5.9): fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to version 3.3.2, the fast-jwt library does not…
CVE-2026-35040 — Medium (CVSS 5.3): fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.2.1, using certain modifiers on RegExp objects…
CVE-2026-35041 — 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…

All CVEs affecting Nearform Fast-jwt →

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