CVE-2016-9910: The serializer in html5lib before 0.99999999 might allow remote attackers to conduct cross-site scripting (XSS

Q: How do I fix CVE-2016-9910?

html5lib: upgrade to newer than 0.99999999. Exact commands for each OS are on this page.

Q: Is CVE-2016-9910 being exploited?

CVE-2016-9910 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2016-9910 affect?

CVE-2016-9910 affects html5lib. Severity is medium (CVSS 6.1). The serializer in html5lib before 0.99999999 might allow remote attackers to conduct cross-site scripting (XSS) attacks by leveraging mishandling of special characters in attribute values, a different vulnerability than CVE-2016-9909.

Q: How urgent is CVE-2016-9910?

Priority 42/100. No elevated risk signals yet.

This month

MEDIUM 6.1UPGRADE

CVE-2016-9910 is a medium-severity flaw (CVSS 6.1) affecting html5lib. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The serializer in html5lib before 0.99999999 might allow remote attackers to conduct cross-site scripting (XSS) attacks by leveraging mishandling of special characters in attribute values, a different vulnerability than CVE-2016-9909.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	2.2% (top 18%)
CISA exploited list	No
Weakness	CWE-79
Published	2017-02-22
Last modified	2026-06-17

Publisher (CNA): Red Hat, Inc. · Vendor: html5lib

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2017-02-22 16:59 UTCPublished CVE record published
2026-06-17 00:56 UTCUpdated Record last modified

html5lib html5lib UPGRADE

Affected: <= 0.99999999

Fixed in: newer than 0.99999999

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy html5lib || rpm -q html5lib || html5lib --version

2. UPGRADE to newer than 0.99999999 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade html5lib

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade html5lib

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2016-9910?

html5lib: upgrade to newer than 0.99999999. Exact commands for each OS are on this page.

Is CVE-2016-9910 being exploited?

CVE-2016-9910 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2016-9910 affect?

CVE-2016-9910 affects html5lib. Severity is medium (CVSS 6.1). The serializer in html5lib before 0.99999999 might allow remote attackers to conduct cross-site scripting (XSS) attacks by leveraging mishandling of special characters in attribute values, a different vulnerability than CVE-2016-9909.

How urgent is CVE-2016-9910?

Priority 42/100. No elevated risk signals yet.

Related CVEs

CVE-2016-9909 MEDIUM 6.1 UPGRADE The serializer in html5lib before 0.99999999 might allow remote attackers to conduct cross-site scripting (XSS

References

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