CVE-2026-1077238.1HighCWE-1287

CVE-2026-107723: fast-jwt : Silent claim-validator bypass when JWT payload is a JSON array

nearform · fast-jwt

Affected: nearform fast-jwt · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.5%probability of exploitation in the next 30 days

40th percentile

050100

Higher than 40% of scored CVEs

8.1HighCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

fast-jwt provides fast JSON Web Token (JWT) implementation. Prior to 6.3.0, fast-jwt createVerifier accepts a validly signed JWT whose payload is a JSON array because src/decoder.js checks that the payload is an object but does not reject arrays. The claim validator loop then finds no named exp, nbf, iss, aud, sub, jti, or nonce properties and silently skips those configured checks, returning the array as a successfully verified payload. An attacker who can produce or influence a validly signed token may bypass expiry, issuer, audience, subject, revocation, and replay protections. The opt-in requiredClaims option can block missing claims, and signature verification itself is not bypassed. This issue is fixed in version 6.3.0.

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

nearform · fast-jwt< 6.3.0

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Improper Validation of Specified Type of Input · Input Validation and Logic
Vendor: nearform
Published: October 2026
Band: Unlikely (under 1%), October 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-107723 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.