Apache HTTP Server: buffer overflow in mod_proxy_ajp via ajp_msg_check_header()

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Summary

CVECVE-2026-28780
StatePUBLISHED
Assignerapache
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-05 22:16:00 UTC
Updated2026-05-06 20:31:10 UTC
DescriptionHeap-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.

Risk And Classification

Primary CVSS: v3.1 9.8 CRITICAL from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Problem Types: CWE-122 | CWE-122 CWE-122 Heap-based Buffer Overflow

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Apache Http Server All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Apache Software Foundation Apache HTTP Server affected 2.4.66 semver Not specified

References

ReferenceSourceLinkTags
httpd.apache.org/security/vulnerabilities_24.html [email protected] httpd.apache.org Release Notes, Vendor Advisory
www.openwall.com/lists/oss-security/2026/05/05/9 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com Mailing List, Third Party Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Andrew Lacambra (en)

CNA: Elhanan Haenel (en)

CNA: Tianshuo Han (<[email protected]>) (en)

CNA: Tristan Madani (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-02-04T12:00:00.000Zreported
CNA2026-03-18T12:00:00.000Zreported by 3rd finder
CNA2026-02-28T12:00:00.000Zreported by 2nd finder
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