Vulnerability · Published Aug 12, 2026 · Assigned by GitHub_M

CVE-2026-73492Loofah `allowed_uri?` does not detect `javascript:` URIs split by numeric character references without semicolons

Low 2.3

In plain English

A low-severity cross-site scripting in loofah from flavorjones. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 34% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)2.3Low

Exploit odds (30 days)0.4%top 66.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

Loofah is a general library for manipulating and transforming HTML/XML documents and fragments, built on top of Nokogiri. From 2.25.0 until 2.25.2, Loofah::HTML5::Scrub.allowed_uri? does not reject javascript: or vbscript: URIs whose scheme is split by semicolon-less numeric character references such as &#58, &#9, &#10, or &#13. CGI.unescapeHTML leaves these references encoded, so allowed_uri? reports the URL safe even though a browser decodes an encoded colon or strips encoded whitespace and executes the resulting URI scheme. This issue affects only callers that pass HTML-encoded strings directly to allowed_uri?; Loofah's default sanitize() path is not affected. This issue is fixed in version 2.25.2.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	ruby-loofah	no fix listed	DEBIAN-CVE-2026-73492
Debian:13	ruby-loofah	no fix listed	DEBIAN-CVE-2026-73492
Debian:14	ruby-loofah	2.25.2-1	DEBIAN-CVE-2026-73492
RubyGems	loofah	2.25.2	GHSA-5qhf-9phg-95m2
Ubuntu:22.04:LTS	ruby-loofah	no fix listed	UBUNTU-CVE-2026-73492
Ubuntu:24.04:LTS	ruby-loofah	no fix listed	UBUNTU-CVE-2026-73492
Ubuntu:26.04:LTS	ruby-loofah	no fix listed	UBUNTU-CVE-2026-73492
Ubuntu:26.10	ruby-loofah	no fix listed	UBUNTU-CVE-2026-73492

Affected products (as reported)

Vendor	Product	Versions
flavorjones	loofah	>= 2.25.0, < 2.25.2

Weakness: CWE-79, CWE-184 · Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

References

https://github.com/flavorjones/loofah/security/advisories/GHSA-5qhf-9phg-95m2 x_refsource_CONFIRM
https://github.com/flavorjones/loofah/pull/308 x_refsource_MISC
https://github.com/flavorjones/loofah/commit/f1be9d893b5a8dd79240441a912d8897e74c38c0 x_refsource_MISC
https://github.com/flavorjones/loofah/releases/tag/v2.25.2 x_refsource_MISC