CVE-2026-104828
Applications that use htmlunit-neko in an HTML sanitizer, content filter, or other parse-transform-serialize pipeline can therefore turn attacker-controlled encoded text into executable markup when the output is rendered by a browser.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.32%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
HtmlUnit Neko is an HtmlUnit adaptation of NekoHTML. Prior to 5.4.0, HTMLWriterFilter writes decoded TEXTAREA and TITLE character content without entity encoding because both elements are treated as special content. During a parse-and-serialize round trip, entity references inside these escapable raw-text elements are decoded by the parser and then emitted as raw markup by printCharacters(), changing the document's semantics. Applications that use htmlunit-neko in an HTML sanitizer, content filter, or other parse-transform-serialize pipeline can therefore turn attacker-controlled encoded text into executable markup when the output is rendered by a browser. This issue is fixed in version 5.4.0.
- CVSS 3.1
- 7.2 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
- EPSS
- 0.32% probability · 25th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-79
- Source
- security-advisories@github.com
EPSS moved from 0.3% on 16 October 2026 to 0.3% on 26 October 2026.
References
- https://github.com/HtmlUnit/htmlunit-neko/commit/c165891e0753aef3e05f5daa6250d3e8d4ada3c0
- https://github.com/HtmlUnit/htmlunit-neko/releases/tag/5.4.0
- https://github.com/HtmlUnit/htmlunit-neko/security/advisories/GHSA-39xg-prhf-8785
- https://github.com/HtmlUnit/htmlunit-neko/security/advisories/GHSA-39xg-prhf-8785
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.