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VulnerabilityPublished

CVE-2026-44351: nearform fast-jwt · Improper Authentication

Affects nearform fast-jwtSource CVE Database V5

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Not known to be exploited · CVSS 9.1 Critical : upgrade to 6.2.4 as a priority.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score
9.1Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 16% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 6.2.4
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 13 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    Public exploit code: GitHub proofs of concept

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Upgrade nearform fast-jwt to 6.2.4.

Affected software

ProductAffectedFixed in
nearformfast-jwtAffected
  • <6.2.4
Fixed in
  • 6.2.4
npmfast-jwtpkg:npm/fast-jwtOther threatsAffected
  • <6.2.4
Fixed in
  • 6.2.4

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in fast-jwt version 6.2.4. Users should upgrade to version 6.2.4 or later to remediate this vulnerability. Since this is a cloud service, the vendor manages remediation for the cloud-hosted service; users should verify with the vendor that their environment is updated. Patch status is confirmed as fixed in 6.2.4. No additional mitigations are specified.

Description

fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.2.4, a critical authentication-bypass vulnerability in fast-jwt's async key-resolver flow allows any unauthenticated attacker to forge arbitrary JWTs that are accepted as authentic. When the application's key resolver returns an empty string (''), for example via the common keys[decoded.header.kid] || '' JWKS-style fallback, fast-jwt converts it to a zero-length Buffer, hands it to crypto.createSecretKey, derives allowedAlgorithms = ['HS256','HS384','HS512'] from it, and then verifies the token's signature against an empty-key HMAC. The attacker simply computes HMAC-SHA256(key='', input='${header}.${payload}'), which Node accepts without complaint — and the verifier returns the attacker-chosen payload (sub, admin, scopes, etc.) as authentic. This vulnerability is fixed in 6.2.4.

References

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