CVE-2026-28780 | 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.

Published: 2026-05-05 Last update: 2026-05-06 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-28780 is rated Moderate Risk (41.9/100): CVSS Critical severity, with low exploitation likelihood (EPSS 0.03%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-28780

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-22 0.07% 0.03% -0.04%
2 2026-05-07 0.02% 0.07% +0.05%
3 2026-05-06 — 0.02% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-28780

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2026-28780

GitHub Security Advisory for CVE-2026-28780

GHSA-wpww-4qvv-xpv8 · Severity: critical — Heap-based Buffer Overflow vulnerability in mod_proxy_ajp of Apache HTTP Server. If mod_proxy_ajp...

OS Trackers for CVE-2026-28780

vendor priority summary link
debian not yet assigned CVE-2026-28780 not yet assigned priority: Debian including 1 source packages (apache2), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2026-28780
redhat high — https://access.redhat.com/security/cve/CVE-2026-28780
suse medium — https://www.suse.com/security/cve/CVE-2026-28780/
ubuntu low CVE-2026-28780 low priority: Ubuntu including 1 source packages (apache2), 9 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): released 5, needs-triage 4. https://ubuntu.com/security/CVE-2026-28780

Affected software / configurations for CVE-2026-28780

Vendor Product Version Raw CPE
apache http_server < 2.4.67 cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:*

References for CVE-2026-28780

URL Tags
https://httpd.apache.org/security/vulnerabilities_24.html Release Notes Vendor Advisory
http://www.openwall.com/lists/oss-security/2026/05/05/9 Mailing List Third Party Advisory
cvelogic Threat Intelligence