Answer in brief
CVE-2026-66843 records a Low severity (CVSS 2.3) vulnerability in html_sanitize_ex HTML5 scrubber keeps attacker-supplied `<object>` elements, allowing untrusted content embedding. 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 2.3. 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 <bec27fec4de99e40c68c4285a610e09e791a3eaf | bec27fec4de99e40c68c4285a610e09e791a3eaf |
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
Inclusion of Functionality from Untrusted Control Sphere vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows a remote attacker to load a document of their choosing into a trusted page via the data attribute of an <object> element in sanitized HTML. object is the one URI-bearing element in lib/html_sanitize_ex/scrubber/html5.ex never registered through allow_tag_with_uri_attributes/3, and its only guard is a prefix match on lowercase "javascript:", so mixed-case variants, data: URIs, protocol-relative URLs and same-origin paths all survive. This is not unconditional cross-site scripting. A javascript: URL does not execute through <object data> in current browsers, data: documents load in an opaque origin, and host-origin script execution additionally requires the application to serve attacker-controlled content from a same-origin path. 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-2026-66843 records a Low severity (CVSS 2.3) vulnerability in html_sanitize_ex HTML5 scrubber keeps attacker-supplied `<object>` elements, allowing untrusted content embedding. 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 2.3. 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 <bec27fec4de99e40c68c4285a610e09e791a3eaf | bec27fec4de99e40c68c4285a610e09e791a3eaf |
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
Inclusion of Functionality from Untrusted Control Sphere vulnerability in the HTML5 scrubber in rrrene html_sanitize_ex allows a remote attacker to load a document of their choosing into a trusted page via the data attribute of an <object> element in sanitized HTML. object is the one URI-bearing element in lib/html_sanitize_ex/scrubber/html5.ex never registered through allow_tag_with_uri_attributes/3, and its only guard is a prefix match on lowercase "javascript:", so mixed-case variants, data: URIs, protocol-relative URLs and same-origin paths all survive. This is not unconditional cross-site scripting. A javascript: URL does not execute through <object data> in current browsers, data: documents load in an opaque origin, and host-origin script execution additionally requires the application to serve attacker-controlled content from a same-origin path. This issue affects html_sanitize_ex: from 0.3.1 before 1.5.3.
Quoted source text, attributed separately from HOL analysis.