PatchSiren

PatchSiren cyber security CVE debrief

CVE-2026-53776 PerryTS CVE debrief

CVE-2026-53776 is a critical vulnerability in Perry before version 0.5.1166. The vulnerability 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. This enables attackers in possession of a previously issued bearer token to present expired tokens to any jwt.verify() call and retain authenticated access indefinitely, effectively bypassing force-expired sessions such as user logout or administrative revocation.

Vendor
PerryTS
Product
perry
CVSS
CRITICAL 9.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-16
Original CVE updated
2026-07-14
Advisory published
2026-06-16
Advisory updated
2026-07-14

Who should care

Users of Perry before version 0.5.1166 should update to version 0.5.1166 or later to mitigate this vulnerability. Attackers can exploit this vulnerability to bypass token expiration and retain authenticated access indefinitely.

Technical summary

The vulnerability is caused by the unconditional setting of validate_exp = false in the verify_decode helper within the stdlib JWT verification path. This allows attackers to bypass token expiration and retain authenticated access indefinitely.

Defensive priority

high

Recommended defensive actions

  • Update Perry to version 0.5.1166 or later.
  • Review and update any custom JWT verification implementations to ensure proper validation of token expiration.

Evidence notes

The CVE record and NVD detail can be found at [cve-org] and [nvd], respectively. Additional information can be found at [ref-4], [ref-5], and [ref-6].

Sources and references

Verified primary and authoritative sources

  • CVE-2026-53776 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-53776

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-53776 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-53776

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.