CVE-2026-7808

justhtml before 1.16.0 contains multiple HTML sanitization bypass issues that can allow active/dangerous content (e.g., script or style) to survive sanitization, potentially leading to cross-site scripting. The issues primarily affect advanced usage rather than the default JustHTML(..., sanitize=True) path for ordinary parsed HTML: mutating or reusing sanitization policy objects (including exported defaults) could weaken later sanitization; programmatic DOM input to sanitize()/sanitize_dom() could miss mixed-case tag names (e.g., ScRiPt, StYlE); crafted programmatic doctype names could serialize into active markup; and custom policies preserving SVG or MathML could allow animation elements, presentation attributes with external url(...) references, or DOM trees mislabeled as namespace="html" to bypass foreign-content checks. Fixed in 1.16.0.

CVSS v3 9.8 CRITICAL

9.8^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-4p64-v8f5-r2gx
https://www.vulncheck.com/advisories/justhtml-before-multiple-security-issues-via-sanitization

Configurations

No configuration.

History

No history.

Information

Published : 2026-08-23 14:16

Updated : 2026-08-26 17:10

NVD link : CVE-2026-7808

Mitre link : CVE-2026-7808

CVE.ORG link : CVE-2026-7808

JSON object : View

Products Affected

No product.

CWE

CWE-20

Improper Input Validation

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