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Libxml2 CVE-2026-86139

| EUVDEUVD-2026-71832 HIGH
Integer Overflow or Wraparound (CWE-190)
2026-09-05 mitre GHSA-xvw4-gjw8-rw38
Buffer Overflow Integer Overflow Libxml2
7.8
CVSS 3.1 · NVD
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Vulnerability Assessment

Weakness
CWE
CWE-190
ASVS 5.0
V15 - Secure Coding and Architecture Integer overflow checks
MITRE ATT&CK

1 technique across 1 tactic: Execution

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

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This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 16, 2026

An integer overflow in libxml2's xmlURIEscapeStr() URI-escaping routine, present in all versions before 2.15.4, allows heap memory corruption that can lead to code execution in the context of the process using the library (CVSS 7.8, AV:L/PR:L). The issue is reachable only by a local, low-privileged actor who can drive an oversized string into libxml2's URI handling helpers, and CISA's SSVC rates it non-automatable with no known exploitation. No public exploit code or CISA KEV listing was identified; EPSS is 0.11% (1st percentile), and the fix landed upstream in the 2.15.4 release and in Red Hat errata RHSA-2026:64463.

Affected VersionsENISA

libxml2 0 <2.15.4

Affected Packages

euvd libxml2 fix: 2.15.4

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

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  • Exploit and PoC references, threat intelligence from 22 sources
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Severity by source

Vendor (mitre) PRIMARY MEDIUM
NVD 7.8 HIGH
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vuln.today AI 7.7 HIGH

libxml2 routinely processes network-supplied URI data in web and XML applications, supporting AV:N; AC:H retained for the precision required to trigger the length wrap-to-zero condition.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L
4.0 AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N
SUSE 6.9 MEDIUM
AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:H
Red Hat 6.9 MEDIUM

Primary rating from Vendor (mitre).

CVSS VectorNVD

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

5
Analysis Updated
Sep 15, 2026 - 19:57 vuln.today
v2 - CVSS changed
Severity Changed
Sep 15, 2026 - 19:52 NVD
MEDIUM HIGH
CVSS changed
Sep 15, 2026 - 19:52 NVD
6.9 (MEDIUM) 7.8 (HIGH)
Patch available
Sep 05, 2026 - 06:01 EUVD
CVE Published
Sep 05, 2026 - 04:23 cve.org
MEDIUM 6.9

DescriptionNVD

In libxml2 before 2.15.4, xmlURIEscapeStr in uri.c has an integer overflow.

Threat Intelligence Overview

EPSS Score
0.1%
Top 99% exploitable
Data Quality
8 sources
Confidence: High
EUVD 🇯🇵JVN NVD CVE.org EPSS Vulnrichment MSRC Vendor GitHub VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.1%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Small
Automatable
No
Human Impact· derived
High
Technical Impact
Total

Priority Score

39
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +39
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Buffer Overflow HIGH

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Integer Overflow MEDIUM

Integer overflow occurs when an arithmetic operation produces a result that exceeds the maximum value a given integer type can store.

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Same weakness CWE-190 – Integer Overflow or Wraparound

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CVE-2026-97229 CRITICAL POC
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Same technique Buffer Overflow

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CVE-2009-0927 HIGH POC
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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Not-Affected
SUSE Linux Enterprise Desktop 15 SP7 Not-Affected
SUSE Linux Enterprise Micro 5.3 Not-Affected
SUSE Linux Enterprise Micro 5.4 Not-Affected
SUSE Linux Enterprise Micro 5.5 Not-Affected

References

Advisories & patches
ADVISORY https://access.redhat.com/errata/RHSA-2026:64463 ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-86139 ADVISORY https://seclists.org/oss-sec/2026/q3/657 ADVISORY https://ubuntu.com/security/notices/USN-8910-1 ADVISORY https://vuldb.com/vuln/399212 REF https://github.com/GNOME/libxml2/commit/8edbbdb09f24d26a2f900141fddc2b9d014f53b0 REF https://github.com/GNOME/libxml2/compare/v2.15.3...v2.15.4

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