Answer in brief
CVE-2026-66370 records a Medium severity (CVSS 4.8) vulnerability in html_sanitize_ex HTML5 scrubber keeps attacker-supplied form-association attributes, allowing form hijacking. The current sources do not mark it as known exploited. The current feed maps rrrene/html_sanitize_ex (generic), rrrene/html_sanitize_ex (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 4.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps rrrene/html_sanitize_ex (generic), rrrene/html_sanitize_ex (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| rrrene/html_sanitize_exgeneric | >=0.3.1 <1.5.3 | 1.5.3 |
| rrrene/html_sanitize_exgeneric | >=8976d64ea0b77d26093a94a43ec48a3978e8d028 <a1e804ed997e780ea71d14393cf2f701330553a6 | a1e804ed997e780ea71d14393cf2f701330553a6 |
Published upstream
Aug 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 6, 2026
URL Redirection to Untrusted Site ('Open Redirect') vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows an unauthenticated remote attacker to retarget a form already on the rendering page and receive whatever the victim submits, including credentials, via the form and formaction attributes on an <input> element in sanitized HTML. HTML's form attribute associates an input with any form on the page by its id even when the input sits outside that form, and formaction on a submit control overrides the owning form's action. Neither attribute receives a scheme check, so an absolute cross-origin URL survives sanitizing. No script executes. The scrubber allows neither form nor button, so the attacker cannot introduce a form of their own and the rendering page must already contain a form carrying an id. This issue affects html_sanitize_ex: from 0.3.1 before 1.5.3.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2026-66370 records a Medium severity (CVSS 4.8) vulnerability in html_sanitize_ex HTML5 scrubber keeps attacker-supplied form-association attributes, allowing form hijacking. The current sources do not mark it as known exploited. The current feed maps rrrene/html_sanitize_ex (generic), rrrene/html_sanitize_ex (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 4.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps rrrene/html_sanitize_ex (generic), rrrene/html_sanitize_ex (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| rrrene/html_sanitize_exgeneric | >=0.3.1 <1.5.3 | 1.5.3 |
| rrrene/html_sanitize_exgeneric | >=8976d64ea0b77d26093a94a43ec48a3978e8d028 <a1e804ed997e780ea71d14393cf2f701330553a6 | a1e804ed997e780ea71d14393cf2f701330553a6 |
Published upstream
Aug 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 6, 2026
URL Redirection to Untrusted Site ('Open Redirect') vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows an unauthenticated remote attacker to retarget a form already on the rendering page and receive whatever the victim submits, including credentials, via the form and formaction attributes on an <input> element in sanitized HTML. HTML's form attribute associates an input with any form on the page by its id even when the input sits outside that form, and formaction on a submit control overrides the owning form's action. Neither attribute receives a scheme check, so an absolute cross-origin URL survives sanitizing. No script executes. The scrubber allows neither form nor button, so the attacker cannot introduce a form of their own and the rendering page must already contain a form carrying an id. This issue affects html_sanitize_ex: from 0.3.1 before 1.5.3.
Quoted source text, attributed separately from HOL analysis.