PatchSiren

PatchSiren cyber security CVE debrief

CVE-2026-56410 libexpat project CVE debrief

CVE-2026-56410 is an integer overflow vulnerability in xmlwf in libexpat before 2.8.2. The vulnerability has a CVSS score of 6.9 and is classified as MEDIUM. This issue affects systems using xmlwf, particularly in parsing XML content. The vulnerability's impact is localized, requiring local access and specific conditions to be exploited, but it can lead to high impacts on confidentiality, integrity, and low impact on availability. Defenders should assess their exposure, focusing on systems that use xmlwf and libexpat versions before 2.8.2.

Vendor
libexpat project
Product
libexpat
CVSS
MEDIUM 6.9
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-21
Original CVE updated
2026-06-23
Advisory published
2026-06-21
Advisory updated
2026-06-23

Who should care

Organizations and developers using libexpat versions before 2.8.2, especially those utilizing xmlwf for XML parsing, should prioritize assessing their exposure and applying necessary updates or mitigations. This includes reviewing software inventory, checking for vulnerable versions, and ensuring that systems are updated or patched accordingly.

Technical summary

The CVE-2026-56410 vulnerability is caused by an integer overflow in the resolveSystemId function of xmlwf in libexpat before 2.8.2. This issue can be triggered by parsing specific XML content, leading to potential crashes or code execution. The vulnerability is characterized by a CVSS vector of CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L, indicating a local attack vector with high requirements but potential for high impact on confidentiality and integrity, and low impact on availability.

Defensive priority

Medium priority due to localized attack vector but potential for significant impact.

Recommended defensive actions

  • Inventory and assess systems using xmlwf and libexpat versions before 2.8.2.
  • Review and apply the official patch or update to libexpat version 2.8.2 or later.
  • Monitor systems for unusual activity related to XML parsing.
  • Implement compensating controls, such as input validation and content filtering, for unpatched systems.
  • Track exceptions for systems that cannot be immediately patched.

Evidence notes

The primary evidence for this vulnerability comes from the NVD and CVE.org records. The vulnerability affects libexpat before version 2.8.2, specifically in the xmlwf tool. Defenders should verify the version of libexpat in use and check for official advisories or patches from the vendor.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-56410 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-56410

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-56410 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-56410

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.