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CVE-2026-43951 Apache CVE debrief

CVE-2026-43951 is a MEDIUM-severity vulnerability in Apache HTTP Server versions from 2.4.0 through 2.4.67. The vulnerability is caused by an out-of-bounds read issue when using mod_headers and mod_mime with multiple response languages.

Vendor
Apache
Product
HTTP Server
CVSS
MEDIUM 6.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-08
Original CVE updated
2026-07-23
Advisory published
2026-06-08
Advisory updated
2026-07-23

Who should care

Users of Apache HTTP Server versions from 2.4.0 through 2.4.67 should be aware of this vulnerability and take steps to mitigate it.

Technical summary

The vulnerability has a CVSS score of 6.5 and is classified as CWE-125. It can be exploited over the network with low attack complexity and requires no user interaction.

Defensive priority

MEDIUM

Recommended defensive actions

  • Apply the patches or updates provided by the vendor to fix the vulnerability.
  • Refer to the vendor's advisory for more information: [ref-4](https://httpd.apache.org/security/vulnerabilities_24.html).
  • Consider subscribing to the Apache HTTP Server security mailing list for future updates: [ref-5](http://www.openwall.com/lists/oss-security/2026/06/08/10).

Evidence notes

The CVE record and NVD detail pages provide additional information about the vulnerability.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-43951 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-43951

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

  • CVE-2026-43951 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-43951

    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.