How severe is CVE-2026-123202?

No CVSS score has been assigned to CVE-2026-123202 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-123202?

Affected package information for CVE-2026-123202 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2026-123202?

Upgrade the affected component to the fixed release for CVE-2026-123202, or apply your distribution's backported patch — distro builds are often patched at an older version number, so check your vendor's advisory rather than the upstream version alone.

How do I detect CVE-2026-123202 in my code and dependencies?

Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

How do I mitigate CVE-2026-123202 if there is no patch (or I can't update yet)?

Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.

Is CVE-2026-123202 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-123202 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-123202?

CVE-2026-123202 has an EPSS (Exploit Prediction Scoring System) score of 0.7%, placing it in the 54th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-123202?

CVE-2026-123202 is classified as CWE-121 (CWE-121). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-123202 published, and has it been updated?

CVE-2026-123202 was published on November 5, 2026 and was last updated on November 6, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2026-123202: libnxml Memory Corruption

EPSS Exploitation Probability

via FIRST.org ↗

0.7%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs54th percentile — riskier than 54% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Description

libnxml before 0.18.6 contains a stack-based buffer overflow vulnerability in src/nxml_parser.c that allows remote attackers to write past a 1024-byte stack buffer via long XML names. Attackers can supply XML or RSS feeds with a 1022-character element, attribute, DOCTYPE or entity name ending in a multi-byte UTF-8 character to crash parsing applications.

Detection & mitigation playbook

Vulnerability

Detect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Fix
Upgrade the affected component to the fixed release for CVE-2026-123202, or apply your distribution's backported patch — distro builds are often patched at an older version number, so check your vendor's advisory rather than the upstream version alone.
Workarounds
Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant

This vulnerability is rated as an Important severity flaw because an unauthenticated remote attacker can cause a denial of service by triggering an application crash without requiring user interaction. Applications consuming untrusted XML feeds or documents via this parser library can be terminated unexpectedly when…

Workaround published by Red Hat

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

Source: Red Hat security advisory for CVE-2026-123202 (CC BY 4.0)

Frequently Asked Questions

libnxml before 0.18.6 contains a stack-based buffer overflow vulnerability in src/nxml_parser.c that allows remote attackers to write past a 1024-byte stack buffer via long XML names. Attackers can supply XML or RSS feeds with a 1022-character element, attribute, DOCTYPE or entity name ending in a multi-byte UTF-8 character to crash parsing applications.

O3 Security · Impact-Aware SCA

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CVE-2026-123202 — libnxml