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Fencer Intel
low 2.3

CVE-2026-73491 json

Loofah `allowed_uri?` does not detect `javascript:` URIs split by named whitespace character references

published 3mo ago modified 18d ago also EUVD-2026-57628 , GHSA-8whx-365g-h9vv

cvss
2.3
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 34%
public exploits
0
none known

Summary

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: URIs whose scheme is split or prefixed with the HTML5 named whitespace character references 	 or 
. CGI.unescapeHTML leaves those references intact, so allowed_uri? reports the URL safe even though a browser decodes and strips the tab or line feed and executes the resulting javascript: URL. 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.

Patch / fix

  • rubygems loofah 2.25.2
  • loofah_project loofah 2.25.2
  • ruby-loofah Debian 14 2.25.2-1

debian advisories DEBIAN-CVE-2026-73491

  • hawk2 SLE High Availability Extension 16.0, SLES for SAP applications 16.0 2.7.2+git.1788518533.7d4dadd6-160000.1.1

suse advisories SUSE-SU-2026:24195-1SUSE-SU-2026:24250-1

  • hawk2 openSUSE Tumbleweed 2.7.2+git.1792148770.648dcddb-1.1
  • hawk2 openSUSE Leap 16.0 2.7.2+git.1788518533.7d4dadd6-160000.1.1

opensuse advisories openSUSE-SU-2026:12153-1openSUSE-SU-2026:22068-1

Is CVE-2026-73491 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-73491 updated cvss 3.7

rubygem-loofah: Loofah: Cross-Site Scripting via malformed `javascript:` URI parsing

  • Red Hat 3scale API Management Platform 2 3scale-amp2/zync-rhel9, 3scale-amp2/system-rhel8
    affected: no fix planned “Out of support scope”
  • Red Hat Satellite 6 rubygem-loofah 2.25.0-1.el9sat
    affected: no fix available “Fix deferred”
  • Red Hat 3scale API Management Platform 2 3scale-amp2/system-rhel9 Red Hat Satellite 6 tfm-rubygem-graphql, rubygem-loofah 2.22.0-1.el8sat
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2mo ago

Exploit prediction

0.39% chance of exploitation in the next 30 days, higher than 34% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 4.0 2.3 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
CNA 4.0 2.3 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected packages

ecosystem package affected fixed in
rubygems loofah
>=2.25.0, <2.25.2
2.25.2

Affected products

  • flavorjones loofah

Classification

Weakness
  • CWE-184 Incomplete List of Disallowed Inputs

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.