CVE-2026-56412: libexpat before 2.8.2 does not consider XML_TOK_DATA_CHARS in doCdataSection and thus lacks handler call depth

Q: How do I fix CVE-2026-56412?

libexpat: upgrade to 2.8.2. Exact commands for each OS are on this page.

Q: Is CVE-2026-56412 being exploited?

CVE-2026-56412 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-2026-56412 affect?

CVE-2026-56412 affects libexpat. Severity is medium (CVSS 4.9). libexpat before 2.8.2 does not consider XML_TOK_DATA_CHARS in doCdataSection and thus lacks handler call depth tracking for various calls from within handlers in cases of a policy violation. Thus, a use-after-free can occur. NOTE: this issu

Q: How urgent is CVE-2026-56412?

Priority 19/100. No elevated risk signals yet.

Routine

MEDIUM 4.9UPGRADE

CVE-2026-56412 is a medium-severity flaw (CVSS 4.9) affecting libexpat. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

libexpat before 2.8.2 does not consider XML_TOK_DATA_CHARS in doCdataSection and thus lacks handler call depth tracking for various calls from within handlers in cases of a policy violation. Thus, a use-after-free can occur. NOTE: this issue exists because of an incomplete fix for CVE-2026-50219.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	4.9 (Medium)
Attack vector	Local
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 93%)
CISA exploited list	No
Weakness	CWE-416
Published	2026-06-21
Last modified	2026-10-25

Publisher (CNA): MITRE · Vendor: libexpat project

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-21 17:16 UTCPublished CVE record published
2026-10-25 23:10 UTCUpdated Record last modified

libexpat project libexpat UPGRADE

Affected: < 2.8.2

Fixed in: 2.8.2

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 2.8.2 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade libexpat

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-2026-56412?

libexpat: upgrade to 2.8.2. Exact commands for each OS are on this page.

Is CVE-2026-56412 being exploited?

CVE-2026-56412 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-2026-56412 affect?

CVE-2026-56412 affects libexpat. Severity is medium (CVSS 4.9). libexpat before 2.8.2 does not consider XML_TOK_DATA_CHARS in doCdataSection and thus lacks handler call depth tracking for various calls from within handlers in cases of a policy violation. Thus, a use-after-free can occur. NOTE: this issu

How urgent is CVE-2026-56412?

Priority 19/100. No elevated risk signals yet.

Related CVEs

CVE-2026-56403 MEDIUM 6.9 UPGRADE libexpat before 2.8.2 has an integer overflow in storeAtts.
CVE-2026-56406 MEDIUM 6.9 UPGRADE libexpat before 2.8.2 has an integer overflow in XML_ParseBuffer because it lacked a check that was present in
CVE-2026-56407 MEDIUM 6.9 UPGRADE libexpat before 2.8.2 has an integer overflow in doProlog that is related to storeEntityValue and entity textL
CVE-2026-56404 MEDIUM 6.9 UPGRADE libexpat before 2.8.2 has an integer overflow in addBinding.
CVE-2026-56405 MEDIUM 6.9 UPGRADE libexpat before 2.8.2 has an integer overflow in getAttributeId.

References

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