Apache HTTP Server 2.4.66 mod_proxy_ajp Heap Buffer Overflow (CVE-2026-28780)
CVE-2026-28780 Published on May 5, 2026

Apache HTTP Server: buffer overflow in mod_proxy_ajp via ajp_msg_check_header()
Heap-based Buffer Overflow vulnerability in mod_proxy_ajp of Apache HTTP Server. If mod_proxy_ajp connects to a malicious AJP server this AJP server can send a malicious AJP message back to mod_proxy_ajp and cause it to write 4 attacker controlled bytes after the end of a heap based buffer. This issue affects Apache HTTP Server: through 2.4.66. Users are recommended to upgrade to version 2.4.67, which fixes the issue.

Vendor Advisory NVD

Vulnerability Analysis

CVE-2026-28780 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.

Attack Vector:
NETWORK
Attack Complexity:
HIGH
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
HIGH
Integrity Impact:
HIGH
Availability Impact:
HIGH

Timeline

reported

reported by 3rd finder 42 days later.

reported by 2nd finder

Weakness Types

Heap-based Buffer Overflow

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

What is a Memory Corruption Vulnerability?

The software writes data past the end, or before the beginning, of the intended buffer. Typically, this can result in corruption of data, a crash, or code execution. The software may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent write operation then produces undefined or unexpected results.

CVE-2026-28780 has been classified to as a Memory Corruption vulnerability or weakness.


Products Associated with CVE-2026-28780

You can be notified by email with stack.watch whenever vulnerabilities like CVE-2026-28780 are published in these products:

Apache HTTP Server
 
Canonical Ubuntu Linux
 
Red Hat Http Server
 
Red Hat Jboss Core Services
 
Red Hat Enterprise Linux (RHEL)
 
Red Hat Rhel E4s
 
Red Hat Rhel Tus
 
Red Hat Rhel Aus
 
Red Hat Rhel Eus Long Life
 

Affected Versions

Apache Software Foundation Apache HTTP Server: Red Hat JBoss Core Services on RHEL 7 Server: Red Hat JBoss Core Services on RHEL 8: Red Hat Enterprise Linux AppStream (v. 10): Red Hat Enterprise Linux AppStream (v. 8): Red Hat Enterprise Linux AppStream AUS (v.8.4): Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4): Red Hat Enterprise Linux AppStream AUS (v.8.6): Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6): Red Hat Enterprise Linux AppStream E4S (v.8.8): Red Hat Enterprise Linux AppStream TUS (v.8.8): Red Hat Enterprise Linux AppStream (v. 9): Red Hat JBoss Core Services 2.4.62.SP4: Red Hat Enterprise Linux 6: Red Hat Enterprise Linux 7:

Exploit Probability

EPSS
0.66%
Percentile
46.82%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.