CVE-2026-53776

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.

CVSS v3.1 Score

9.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0036

Probability of exploitation

0.28%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-613 CWE-613

References

Other References

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

Frequently Asked Questions

What is CVE-2026-53776? +

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. It has a CVSS v3.1 base score of 9.1 (CRITICAL).

How severe is CVE-2026-53776? +

CVE-2026-53776 has a CVSS v3.1 score of 9.1 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0036, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-53776? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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