Improper Neutralization of Input During Web Page Generation in html5lib
The serializer in html5lib before 0.99999999 might allow remote attackers to conduct cross-site scripting (XSS) attacks by leveraging mishandling of the < (less than) character in attribute values.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | html5lib | < 0.999999999 | 0.999999999 |
References
- https://html5lib.readthedocs.io/en/latest/changes.html#b9
- https://github.com/html5lib/html5lib-python/issues/12
- https://github.com/html5lib/html5lib-python/issues/11
- https://github.com/html5lib/html5lib-python/commit/9b8d8eb5afbc066b7fac9390f5ec75e5e8a7cab7
- http://www.securityfocus.com/bid/95132
- http://www.openwall.com/lists/oss-security/2016/12/08/8
- http://www.openwall.com/lists/oss-security/2016/12/06/5
- https://github.com/advisories/GHSA-v9v9-xffq-rwr4
- https://nvd.nist.gov/vuln/detail/CVE-2016-9909
- https://github.com/html5lib/html5lib-python
- https://github.com/pypa/advisory-database/tree/main/vulns/html5lib/PYSEC-2017-14.yaml
- https://web.archive.org/web/20161229134056/http://www.securityfocus.com/bid/95132
- CVSS vector
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N- Weakness (CWE)
CWE-79- Platform
- Python (PyPI)
- Package
html5lib- Disclosed
- 22.02.2017
- Updated
- 11.10.2026 11:20
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2017-14 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-v9v9-xffq-rwr4 - CC BY 4.0
Vulnerability history: html5lib
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 02.2017 02.2017
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Medium 2
Disclosures per year
- 2017: 2
- 2018: 0
- 2019: 0
- 2020: 0
- 2021: 0
- 2022: 0
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 0
-
Improper Neutralization of Input During Web Page Generation in html5lib this entry
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