CVE-2026-28780: apache software foundation apache http server Heap-based Buffer Overflow
Vulnerability summary
CVE-2026-28780 is a critical (CVSS 9.8) Heap-based Buffer Overflow vulnerability in apache software foundation apache http server. EPSS estimates a 1.63% chance of exploitation in the next 30 days, higher than 75.8% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 18 · Related 8Timeline
- 05-05-2026PublishedVulnerability first disclosed.
- 14-09-2026Last modifiedVulnerability information updated.
Description
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.
CVSS metrics
5 scores · 5 sources · 1 version- OSV · AlpineEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- OSV · UbuntuEcosystem advisory · calculated8.1HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:HDiffers
- OSV · DebianEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- NVDNIST9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
1.63%
Chance of exploitation in the next 30 days
Percentile
76%
Versus all other CVEs
30-day change
+0.26 pp
From 1.38% on 19-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-122Heap-based Buffer OverflowA 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().
- CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.
Affected systems
Alpine1 product
- apache2< 2.4.67-r0
Apache1 product
- http_server< 2.4.67
Apache software foundation1 product
- apache http server≤ 2.4.66
Debian1 product
- apache2< 2.4.67-1~deb12u2 | < 2.4.67-1~deb13u2 | < 2.4.67-1
Ubuntu1 product
- apache2< 2.4.7-1ubuntu4.22+esm13 | < 2.4.18-2ubuntu3.17+esm18 | < 2.4.29-1ubuntu4.27+esm9 | < 2.4.41-4ubuntu3.23+esm4 | < 2.4.52-1ubuntu4.20 | < 2.4.58-1ubuntu8.12 | < 2.4.64-1ubuntu3.4 | < 2.4.66-2ubuntu2.1
5 vendors · 5 products
