Description
HtmlSanitizer before 9.2.1039 and 10.0 prereleases before 10.0.1037-beta contains a cross-site scripting vulnerability because SanitizeDom(string) never sanitizes attributes on the html and body wrapper elements. Attackers can supply input with a second body or html tag carrying event handlers like onload, executing script when applications render serialized document or body outer HTML.
References9
- github.com/mganss/HtmlSanitizer
- github.com/mganss/HtmlSanitizer/blob/v9.2.995/src/HtmlSanitizer…
- github.com/mganss/HtmlSanitizer/blob/v9.2.995/src/HtmlSanitizer…
- github.com/mganss/HtmlSanitizer/commit/96afbc818e64de7571ea1795…
- github.com/mganss/HtmlSanitizer/commit/ab626e7a4f2893f7e9ec0a72…
- github.com/mganss/HtmlSanitizer/releases/tag/v10.0.1037-beta
- github.com/mganss/HtmlSanitizer/releases/tag/v9.2.1039
- joshua.hu/htmlsanitizer-sanitizedom-body-html-attribute-bypass
- www.vulncheck.com/advisories/htmlsanitizer-before-9.2.1039-xss-…
Metrics
- CVSS 3.1
-
4.7
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N - CVSS 4.0
-
2.3
LOW
Score source: CNA
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/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 - EPSS — exploit probability
- 0% percentile: 21 · as of 8 November 2026
- CWE
- CWE-79
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.