5.4

CVE-2026-84371: ApostropheCMS: Stored XSS via SVG SMIL URI-list scheme-policy bypass

Deferred
AliasesCGA-373h-q563-v45pCGA-3xvc-c2j5-c2hmCGA-62c8-7qr5-r73r
Published 01-09-2026Last modified 02-09-2026

Vulnerability summary

CVE-2026-84371 is a medium (CVSS 5.4) Cross-site Scripting vulnerability in apostrophecms apostrophe. EPSS estimates a 0.30% chance of exploitation in the next 30 days, higher than 21.3% of scored vulnerabilities.

Overall risk
22/100
0100
Low · default modelHow is this calculated?
CVSS score
5.4/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.30%
0%100%
Low · +0.11 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 0 · Related 1
CGA-Q9W5-R6PV-F6G3

Timeline

  1. 01-09-2026
    PublishedVulnerability first disclosed.
  2. 02-09-2026
    Last modifiedVulnerability information updated.

Description

ApostropheCMS is an open-source Node.js content management system, and sanitize-html provides a simple HTML sanitizer with a clear API. From version 1.9.0 until version 2.17.7, packages/sanitize-html/index.js validates an animation value attribute as one flat URL and does not recognize that attributeName selecting href or xlink:href gives the sibling values, from, to, or by attribute SVG SMIL URL semantics. In configurations that allow the animate, animateColor, animateMotion, animateTransform, or set elements, a values list can begin with a safe fragment and contain a later executable destination that survives allowedSchemesAppliedToAttributes checking. When the sanitized SVG is rendered, the browser can copy that later destination into the live link, and a victim who activates the link can execute script in the application's origin. This issue is fixed in version 2.17.7.

CVSS metrics

5 scores · 5 sources · 1 version

EPSS trend

Probability

0.30%

Chance of exploitation in the next 30 days

Percentile

21%

Versus all other CVEs

30-day change

Increase +0.11 pp

From 0.18% on 22-09-2026

22-09-202622-10-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Chainguard4 products
  • jupyter-base-notebook< 7.6.3-r2
  • tensorflow-gpu-jupyter< 2.21.0-r9
  • unleash< 8.1.0-r2
  • unleash-fips< 8.1.0-r2
Apostrophecms1 product
Npm1 product
  • sanitize-html≥ 1.9.0, < 2.17.7
Wolfi1 product
  • jupyter-base-notebook< 7.6.3-r2

4 vendors · 7 products

References

8 links