Resource exhaustion in Lin-Snow Ech0
CVE-2026-79658
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).
Vulnerability class: DoS (Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.005 (41.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 42nd percentile — 41.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002
Affected products
Weakness classification (CWE)
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)
Frequently asked questions
- What is CVE-2026-79658?
- CVE-2026-79658 is a high-severity vulnerability in Lin-Snow Ech0, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2026-08-25.
- How severe is CVE-2026-79658?
- High severity. CVSS v3 base score is 7.5 out of 10.