CVE-2026-86137: In libxml2 before 2.15.4, xmlFAParsePosCharGroup has an out-of-bounds read, aka an out-of-bounds read in the N

Q: How do I fix CVE-2026-86137?

libxml2: upgrade to 2.15.4. Exact commands for each OS are on this page.

Q: Is CVE-2026-86137 being exploited?

CVE-2026-86137 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-2026-86137 affect?

CVE-2026-86137 affects libxml2. Severity is low (CVSS 2.9). In libxml2 before 2.15.4, xmlFAParsePosCharGroup has an out-of-bounds read, aka an out-of-bounds read in the NXT macro in xmlregexp.

Q: How urgent is CVE-2026-86137?

Priority 17/100. Public exploit reference

Routine

LOW 2.9UPGRADE

CVE-2026-86137 is a low-severity flaw (CVSS 2.9) affecting libxml2. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In libxml2 before 2.15.4, xmlFAParsePosCharGroup has an out-of-bounds read, aka an out-of-bounds read in the NXT macro in xmlregexp.

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	2.9 (Low)
Attack vector	Local
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 91%)
CISA exploited list	No
Weakness	CWE-125
Published	2026-09-05
Last modified	2026-09-15

Publisher (CNA): MITRE · Vendor: xmlsoft

Last updated 2026-09-15 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-05 05:17 UTCPublished CVE record published
2026-09-15 19:46 UTCUpdated Record last modified

xmlsoft libxml2 UPGRADE

Affected: < 2.15.4

Fixed in: 2.15.4

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy libxml2 || rpm -q libxml2 || libxml2 --version

2. UPGRADE to 2.15.4 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade libxml2

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade libxml2

Note

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

Advisories and coverage

Official advisories

Amazon Linux 2 ALAS: ALAS2-2026-3940 (medium): libxml2 2026-09-28

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-2026-86137?

libxml2: upgrade to 2.15.4. Exact commands for each OS are on this page.

Is CVE-2026-86137 being exploited?

CVE-2026-86137 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-2026-86137 affect?

CVE-2026-86137 affects libxml2. Severity is low (CVSS 2.9). In libxml2 before 2.15.4, xmlFAParsePosCharGroup has an out-of-bounds read, aka an out-of-bounds read in the NXT macro in xmlregexp.

How urgent is CVE-2026-86137?

Priority 17/100. Public exploit reference

Software pages

libxml2 vulnerabilities

Related CVEs

CVE-2026-6732 MEDIUM 6.5 UPGRADE MITIGATE A flaw was found in libxml2
CVE-2026-6653 CRITICAL 9.8 UPGRADE Use After Free in libxml2's xmlParseInternalSubset from GNOME libxml2 version 2.9.11 to 2.11.0 allows a remote
CVE-2026-11979 HIGH 7.8 UPGRADE libxml2 is vulnerable to multiple stack-based buffer overflows in the xmlcatalog utility when running in --she
CVE-2026-86138 MEDIUM 6.9 UPGRADE In libxml2 before 2.15.4, xmlDictAddQString in dict.c has an integer overflow and resultant heap-based buffer
CVE-2026-86139 MEDIUM 6.9 UPGRADE In libxml2 before 2.15.4, xmlURIEscapeStr in uri.c has an integer overflow.

References

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