CVE-2016-3709Public exploitNetwork attack vector

Cross-site scripting via unquoted SSI attribute content

Published Jul 28, 2022 · Updated Nov 4, 2025

Cross-site scripting in libxml2 2.9.2 through 2.9.10 allows remote attackers to inject script nodes via crafted HTML input. HTMLtree.c's htmlAttrDumpOutput treats server-side-include markers inside URI attributes as raw spans and writes them without attribute quoting. Exploitation requires a consuming application to parse attacker-controlled HTML and a user to view its browser-rendered serialized output.

CVSS severity6.1
Medium
EPSS probability0.90%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in libxml2 2.9.2 through 2.9.10 allows remote attackers to inject script nodes via crafted HTML input. HTMLtree.c's htmlAttrDumpOutput treats server-side-include markers inside URI attributes as raw spans and writes them without attribute quoting. Exploitation requires a consuming application to parse attacker-controlled HTML and a user to view its browser-rendered serialized output.

The record

CVE
CVE-2016-3709
Published
Jul 28, 2022
Updated
Nov 4, 2025
Vendor
XMLSoft
Product
libxml2
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 28, 2022CVE publishedPublication date reported by the CVE source.
  2. Nov 4, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.9.x

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

XMLSoft · libxml2version=2.9.x

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007Command and Scripting Interpreter: JavaScript

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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