Ech0 before 4.7.3 Access Token Revocation Bypass

published 2026-05-07 6 mo ago modified 2026-10-08 31 d ago also GHSA-fpw6-hrg5-q5x5 , GO-2026-5375 , EUVD-2026-65450

cvss: 7.4; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 29%
public exploits: 0; none known

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.

Patch / fix

fixed in 2 links 1

go github.com/lin-snow/ech0 1.4.8-0.20260503041146-eab62379c795
lin-snow Ech0 4.7.3

github.com/lin-snow/Ech0@eab6237 commit

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: total
Assessed: 2 mo ago (2026-08-25)

Exploit prediction

0.36% chance of exploitation in the next 30 days, higher than 29% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/lin-snow/Ech0/security/advisories/GHSA-fpw6-hrg5-q5x5 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	9.1	CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
CNA	3.1	7.4	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
CNA	4.0	9.1	CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
GitHub	3.1	7.4	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected packages

ecosystem	package	affected	fixed in
go	github.com/lin-snow/ech0	<1.4.8-0.20260503041146-eab62379c795	1.4.8-0.20260503041146-eab62379c795

Affected products

lin-snow Ech0

Classification

Weakness

CWE-613 DEPRECATED: Insufficient Session Expiration
CWE-755 Improper Handling of Exceptional Conditions

References

github.com /lin-snow/Ech0/commit/eab62379c795c3f4850a9ca938ae3f27d7171541
web
github.com /lin-snow/Ech0/security/advisories/GHSA-fpw6-hrg5-q5x5
vendor-advisory, exploit, web, advisory
vulncheck.com /advisories/ech0-before-access-token-revocation-bypass
third-party-advisory
github.com /lin-snow/Ech0
package

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary