CVE-2016-9909 json
Improper Neutralization of Input During Web Page Generation in html5lib
published 2017-02-22 9 y ago modified 2026-06-17 4 mo ago also GHSA-v9v9-xffq-rwr4 , PYSEC-2017-14 , EUVD-2017-0060
- cvss
- 6.1
- version 3.0, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 2.2%
- EPSS 2.2% chance of exploitation in 30 days, percentile 82%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- pypi html5lib 0.999999999
- html5lib Debian 14, Debian 13, Debian 12 0.999999999-1
debian advisories DEBIAN-CVE-2016-9909
- python-html5lib Arch Linux 0.999999999-1
arch linux advisories AVG-100
Vendor advisories
What the vendors themselves say about their products: affected, fixed or not affected, and what to do.
red hat product security vex CVE-2016-9909 updated cvss 6.1
python-html5lib: XSS due to unquoted attributes that need escaping in legacy browsers
-
Red Hat All currently supported Red Hat productsnot affected: vulnerable code not present
Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf
Exploit prediction
2.16% chance of exploitation in the next 30 days, higher than 82% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.0 | 6.1 | CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
| NVD | 2.0 | 4.3 | AV:N/AC:M/Au:N/C:N/I:P/A:N |
| GitHub | 3.0 | 6.1 | CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | html5lib | <0.999999999 |
0.999999999 |
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
References
-
github.com
/html5lib/html5lib-python/commit/9b8d8eb5afbc066b7fac9390f5ec75e5e8a7cab7
web, patch
-
openwall.com
/lists/oss-security/2016/12/06/5
mailing-list, web, patch, third-party-advisory
-
openwall.com
/lists/oss-security/2016/12/08/8
mailing-list, web, patch, third-party-advisory
-
github.com
/html5lib/html5lib-python/issues/12
web, vendor-advisory, report
-
github.com
/html5lib/html5lib-python/issues/11
web, vendor-advisory, report
-
html5lib.readthedocs.io
/en/latest/changes.html#b9
web, release-notes
-
securityfocus.com
/bid/95132
vdb-entry, third-party-advisory, web
-
nvd.nist.gov
/vuln/detail/CVE-2016-9909
advisory
-
github.com
/advisories/GHSA-v9v9-xffq-rwr4
advisory
-
github.com
/html5lib/html5lib-python
package
-
github.com
/pypa/advisory-database/tree/main/vulns/html5lib/PYSEC-2017-14.yaml
web
-
web.archive.org
/web/20161229134056/http://www.securityfocus.com/bid/95132
web
Sources
- CVE List CVE-2016-9909
- GitHub Advisory GHSA-v9v9-xffq-rwr4
- NVD CVE-2016-9909
- OSV PYSEC-2017-14
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.