by Kastro
Paper/Archive/CVE-2026-53776

CVE-2026-53776

PerryTS perry — Perry < 0.5.1166 JWT Expiration Bypass via verify_decode

EPSS 0.4%CVSS 9.3
critical.is priorityof 100
34
CVSS 9.3 (CNA)9.3 / 10 × 3027.9Not in CISA KEV+300.0EPSS percentile 29.5.295 × 205.9No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

Perry before 0.5.1166 contains a JWT validation vulnerability that allows remote attackers to bypass token expiration by exploiting the unconditional setting of validate_exp = false in the verify_decode helper within the stdlib JWT verification path. Attackers in possession of a previously issued bearer token can present expired tokens to any jwt.verify() call and retain authenticated access indefinitely, bypassing force-expired sessions such as user logout or administrative revocation.

Affected

ProductAffectedFixed inSource
perry< 0.5.11660.5.1166CNA

Scores by source

VulnCheck (CNA)9.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
VulnCheck (CNA)9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: total

References

refgithub.com/PerryTS/perry/releases/v0.5.1166advisorygithub.com/PerryTS/perry/security/advisories/GHSA-5324-c68v-8w62writeupvulncheck.com/advisories/perry-jwt-expiration-bypass-via-verify-decode