Vulnerability · Published Jun 16, 2026 · Assigned by VulnCheck

CVE-2026-53776Perry < 0.5.1166 JWT Expiration Bypass via verify_decode

Critical 9.1

In plain English

A critical-severity security flaw in perry from PerryTS. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 30% of all known vulnerabilities).

Severity (CVSS 3.1)9.1Critical

Exploit odds (30 days)0.4%top 70.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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 products (as reported)

Vendor	Product	Versions
PerryTS	perry	0 – before 0.5.1166

Weakness: CWE-613 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

References

https://github.com/PerryTS/perry/releases/v0.5.1166 release-notes
https://github.com/PerryTS/perry/security/advisories/GHSA-5324-c68v-8w62 vendor-advisory
https://www.vulncheck.com/advisories/perry-jwt-expiration-bypass-via-verify-decode third-party-advisory