Cross-site Scripting (XSS) Affecting rust-ammonia package, versions *


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.55% (46th percentile)

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  • Snyk IDSNYK-ECHOLATEST-RUSTAMMONIA-21004967
  • published16 Oct 2026
  • disclosed15 Oct 2026

Introduced: 15 Oct 2026

NewCVE-2026-63430  (opens in a new tab)
CWE-79  (opens in a new tab)

How to fix?

There is no fixed version for Echo:latest rust-ammonia.

NVD Description

Note: Versions mentioned in the description apply only to the upstream rust-ammonia package and not the rust-ammonia package as distributed by Echo. See How to fix? for Echo:latest relevant fixed versions and status.

ammonia is a Rust library for repairing and securing untrusted HTML. Prior to 3.3.2, 4.0.2, and 4.1.3, applications that explicitly allow the math tag, annotation-xml, and at least one raw-text HTML element while disallowing the encoding attribute can permit mutation cross-site scripting. ammonia does not correctly implement annotation-xml's encoding-dependent MathML integration-point behavior after attribute filtering removes encoding, so the sanitizer validates a descendant under one namespace interpretation while the browser reparses the output under another. An attacker can use that namespace transition and an allowed raw-text HTML element to execute JavaScript when a user renders the sanitized output. The required tags are not enabled by default, so applications that do not explicitly allow them are not affected. This issue is fixed in versions 3.3.2, 4.0.2, and 4.1.3.

CVSS Base Scores

version 3.1