What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-25 · updated 2026-08-31
• Weakness: CWE-400

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

• lin-snow Ech0: before 5.0.1 — fixed in 5.0.1

How to fix

Upgrade to a fixed version: lin-snow Ech0 5.0.1. Check the vendor advisory for mitigations.

References

• https://github.com/lin-snow/Ech0/security/advisories/GHSA-mqxv-9rm6-w8qc
• https://www.vulncheck.com/advisories/ech0-before-denial-of-service-via-accept-language

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