# CVE-2026-28780: Apache HTTP Server heap overflow in mod_proxy_ajp

Source: https://junglewise.ai/threats/cve-2026-28780-apache-http-server-heap-overflow-in-mod-proxy-ajp  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-05. Updated: 2026-06-30  
License: CC BY 4.0 with a link back

CVE-2026-28780 · Severity: critical · CVSS 9.8 · Published 2026-05-05

The Apache HTTP Server is a widely used web server for hosting websites and applications. A vulnerability in its AJP proxy module allows a malicious backend server to send specially crafted messages that corrupt the web server's memory. This could allow an attacker to take full control of the server, potentially leading to data theft or service disruption.

Technologies: [Apache HTTP Server](https://junglewise.ai/threats/technologies/http-server). Vendors: [Apache](https://junglewise.ai/threats/vendors/apache).

## Quick answers

**Is CVE-2026-28780 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-28780 being exploited in the wild.

**How severe is CVE-2026-28780?** Critical severity, with a CVSS score of 9.8, published 5 May 2026.

**Which products and versions are affected?** Apache HTTP Server through 2.4.66; Red Hat Enterprise Linux 6, 7, 8, 9, 10.2; Red Hat JBoss Core Services 1, 2.4.62.SP4.

**Is there a fix for CVE-2026-28780?** A patch was published on 2026-05-05: Fixed in Apache HTTP Server 2.4.67 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-28780 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-28780?** Check whether you run Apache HTTP Server. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A heap-based buffer overflow exists in the mod_proxy_ajp module of Apache HTTP Server within the ajp_msg_check_header() function. When the server is configured to proxy requests to a backend using the Apache JServ Protocol (AJP), a compromised or malicious backend server can return a crafted AJP message. This message triggers an out-of-bounds write of 4 attacker-controlled bytes past the end of a heap-allocated buffer. While the overflow is small, it can be leveraged for arbitrary code execution or a denial-of-service (crash). The vulnerability is fixed in version 2.4.67.

## Affected products

- Apache HTTP Server through 2.4.66
- Red Hat Enterprise Linux 6, 7, 8, 9, 10.2
- Red Hat JBoss Core Services 1, 2.4.62.SP4

## Timeline

- 2026-02-04: disclosed: Initial report to vendor
- 2026-05-05: advisory: Public disclosure by Apache and Openwall
- 2026-05-05: patched: Fixed in Apache HTTP Server 2.4.67
- 2026-05-27: patched: Red Hat released security updates (RHSA-2026:21391)

## References

- [https://httpd.apache.org/security/vulnerabilities_24.html](https://httpd.apache.org/security/vulnerabilities_24.html)
- [http://www.openwall.com/lists/oss-security/2026/05/05/9](http://www.openwall.com/lists/oss-security/2026/05/05/9)
- [https://access.redhat.com/errata/RHSA-2026:21391](https://access.redhat.com/errata/RHSA-2026:21391)
- [https://access.redhat.com/errata/RHSA-2026:21433](https://access.redhat.com/errata/RHSA-2026:21433)
- [https://access.redhat.com/errata/RHSA-2026:22140](https://access.redhat.com/errata/RHSA-2026:22140)
- [https://access.redhat.com/errata/RHSA-2026:27200](https://access.redhat.com/errata/RHSA-2026:27200)
- [https://access.redhat.com/errata/RHSA-2026:27201](https://access.redhat.com/errata/RHSA-2026:27201)

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