Vulnerability · Published Aug 25, 2026 · Assigned by VulnCheck

CVE-2026-79664Ech0 before 4.7.3 Access Token Revocation Bypass

High 7.4

In plain English

A high-severity security flaw in Ech0 from lin-snow. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 30% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.4High

Exploit odds (30 days)0.4%top 70.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

Ech0 before 4.7.3 fails to properly revoke access tokens created with never-expire option, allowing attackers to maintain perpetual authenticated access after token theft. Three independent revocation mechanisms fail: logout panics on nil ExpiresAt field, RevokeToken skips when remainTTL is zero, and admin delete does not blacklist the JTI, leaving stolen tokens cryptographically valid until JWT secret rotation.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Go	github.com/lin-snow/ech0	1.4.8-0.20260503041146-eab62379c795	GHSA-fpw6-hrg5-q5x5
Go	github.com/lin-snow/ech0	1.4.8-0.20260503041146-eab62379c795	GO-2026-5375

Affected products (as reported)

Vendor	Product	Versions
lin-snow	Ech0	0 – before 4.7.3

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

References

GitHub Security Advisory (GHSA-fpw6-hrg5-q5x5) vendor-advisory
VulnCheck Advisory: Ech0 before 4.7.3 Access Token Revocation Bypass third-party-advisory