6.1

CVE-2026-63670: ApostropheCMS: Mutation-XSS / allowedTags bypass via literal `</textarea/>` solidus close

Deferred
AliasesCGA-2682-pwhf-fpcjCGA-562x-f774-pr7rCGA-cp5q-r5r4-fcmm
Published 17-08-2026Last modified 18-08-2026

Vulnerability summary

CVE-2026-63670 is a medium (CVSS 6.1) Cross-site Scripting vulnerability in apostrophecms apostrophe. EPSS estimates a 0.33% chance of exploitation in the next 30 days, higher than 24.5% of scored vulnerabilities.

Overall risk
24/100
0100
Low · default modelHow is this calculated?
CVSS score
6.1/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.33%
0%100%
Low · +0.04 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Timeline

  1. 17-08-2026
    PublishedVulnerability first disclosed.
  2. 18-08-2026
    Last modifiedVulnerability information updated.

Description

ApostropheCMS is an open-source Node.js content management system. Prior to 2.17.6, sanitizeHtml() can pass disallowed executable markup through packages/sanitize-html/index.js when textarea or xmp is included in allowedTags because a literal solidus after the raw-text end-tag name is treated as text by htmlparser2 and the ontext handler emits that content without escaping, while a browser parses the following img onerror markup as active HTML. This issue is fixed in version 2.17.6.

CVSS metrics

5 scores · 5 sources · 1 version

EPSS trend

Probability

0.33%

Chance of exploitation in the next 30 days

Percentile

25%

Versus all other CVEs

30-day change

Increase +0.04 pp

From 0.29% 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

Chainguard2 products
  • jupyter-base-notebook< 7.6.3-r2
  • tensorflow-gpu-jupyter< 2.21.0-r9
Apostrophecms1 product
Npm1 product
  • sanitize-html< 2.17.6
Wolfi1 product
  • jupyter-base-notebook< 7.6.3-r2

4 vendors · 5 products

References

6 links