Vulnerability · Published Aug 25, 2026 · Assigned by VulnCheck

CVE-2026-79658Ech0 before 5.0.1 Denial of Service via Accept-Language

High 7.5

In plain English

A high-severity uncontrolled resource consumption in Ech0 from lin-snow. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 44% of all known vulnerabilities).

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)0.5%top 56.3% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

Ech0 before 5.0.1 does not impose any size or shape limit on the Accept-Language header processed by its i18n middleware, which runs on every HTTP request. The header is passed unfiltered to go-i18n's NewLocalizer, which internally calls golang.org/x/text/language.ParseAcceptLanguage. The CVE-2022-32149 mitigation in x/text caps '-' characters but not '_' characters, which the parser aliases to '-', allowing quadratic-time parsing to be triggered with a large header (up to Go's default 1 MiB) built from underscore separators. An unauthenticated attacker can send such requests to consume roughly 1.5 seconds of CPU each, and concurrent requests can saturate a multi-core server (denial of service).

Affected products (as reported)

Vendor	Product	Versions
lin-snow	Ech0	0 – before 5.0.1

Weakness: CWE-400 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

GitHub Security Advisory (GHSA-mqxv-9rm6-w8qc) vendor-advisory
VulnCheck Advisory: Ech0 before 5.0.1 Denial of Service via Accept-Language third-party-advisory