CVE-2016-9910: Cross-site Scripting in html5lib
6.1
CVSS Score
3.0
Basic Information
CVE ID
GHSA ID
EPSS Score
0.68165%
CWE
Published
5/17/2022
Updated
9/23/2024
KEV Status
No
Technology
Python
Technical Details
CVSS Vector
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Package Name | Ecosystem | Vulnerable Versions | First Patched Version |
---|---|---|---|
html5lib | pip | < 0.99999999 | 0.99999999 |
Vulnerability Intelligence
Miggo AI
Root Cause Analysis
The vulnerability stems from the attribute quoting logic in the serializer. The commit 9b8d8eb introduced a ternary quote_attr_values system and expanded the regex pattern to include legacy-sensitive characters. The pre-patch code used a boolean flag and a limited regex (quoteAttributeSpec), failing to properly escape attributes containing characters like U+000B or ` which could break attribute context in legacy browsers. The serialize method directly controls attribute serialization and was the focal point of the security fix.