CVE-2026-28780: Heap-based Buffer Overflow vulnerability in mod_proxy_ajp of Apache HTTP Server. If mod_proxy_ajp connects to

Q: How do I fix CVE-2026-28780?

http server: upgrade to 2.4.67. Exact commands for each OS are on this page.

Q: Is CVE-2026-28780 being exploited?

CVE-2026-28780 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-28780 affect?

CVE-2026-28780 affects http server. Severity is critical (CVSS 9.8). 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 con

Q: How urgent is CVE-2026-28780?

Priority 65/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action; On your watchlist

This week

CRITICAL 9.8REMOTEWATCHLISTUPGRADE

CVE-2026-28780 is a critical-severity flaw (CVSS 9.8) affecting http server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Critical severity
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.4% (top 28%)
CISA exploited list	No
Weakness	CWE-122, CWE-787
Published	2026-05-05
Last modified	2026-09-14

Publisher (CNA): Apache Software Foundation · Vendor: apache

Last updated 2026-09-14 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-05 22:16 UTCPublished CVE record published
2026-09-14 13:17 UTCUpdated Record last modified

apache http server UPGRADE

Affected: < 2.4.67

Fixed in: 2.4.67

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy http-server || rpm -q http-server || http-server --version

2. UPGRADE to 2.4.67 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade http-server

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade http-server

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Exact fixes by distribution

Fedora 46 · fzssh · FIXED · 1.4.0-2.fc46 · FEDORA-2026-8004fcd067 · source

sudo dnf upgrade --advisory=FEDORA-2026-8004fcd067

Ubuntu 20.04 · apache2 · FIXED · 2.4.41-4ubuntu3.23+esm4

sudo apt update && sudo apt install --only-upgrade apache2 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' apache2)" ge "2.4.41-4ubuntu3.23+esm4" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 22.04 · apache2 · FIXED · 2.4.52-1ubuntu4.20

sudo apt update && sudo apt install --only-upgrade apache2 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' apache2)" ge "2.4.52-1ubuntu4.20" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 24.04 · apache2 · FIXED · 2.4.58-1ubuntu8.12

sudo apt update && sudo apt install --only-upgrade apache2 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' apache2)" ge "2.4.58-1ubuntu8.12" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 25.10 · apache2 · FIXED · 2.4.64-1ubuntu3.4

sudo apt update && sudo apt install --only-upgrade apache2 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' apache2)" ge "2.4.64-1ubuntu3.4" && echo PATCHED || echo STILL-VULNERABLE

Debian 12 · apache2 · FIXED · 2.4.67-1~deb12u2

sudo apt update && sudo apt install --only-upgrade apache2 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' apache2)" ge "2.4.67-1~deb12u2" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · apache2 · FIXED · 2.4.67-1~deb13u2

sudo apt update && sudo apt install --only-upgrade apache2 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' apache2)" ge "2.4.67-1~deb13u2" && echo PATCHED || echo STILL-VULNERABLE

RHEL 10 · httpd · FIXED · httpd-2.4.63-13.el10_2.1

sudo dnf upgrade --advisory=RHSA-2026:21433 rpm -q httpd

RHEL 10.0 Extended Update Support · httpd · FIXED · httpd-2.4.63-1.el10_0.4

sudo dnf upgrade --advisory=RHSA-2026:47046 rpm -q httpd

RHEL 9 · httpd · FIXED · httpd-2.4.62-13.el9_8.1

sudo dnf upgrade --advisory=RHSA-2026:21391 rpm -q httpd

RHEL 9.2 Update Services for SAP Solutions · httpd · FIXED · httpd-2.4.53-11.el9_2.15

sudo dnf upgrade --advisory=RHSA-2026:67152 rpm -q httpd

RHEL 9.4 Update Services for SAP Solutions · httpd · FIXED · httpd-2.4.57-11.el9_4.5

sudo dnf upgrade --advisory=RHSA-2026:66323 rpm -q httpd

Alpine 3.20 · apache2 · FIXED · apache2-2.4.67-r0

apk add --upgrade apache2 apk info -v apache2

Alpine 3.21 · apache2 · FIXED · apache2-2.4.67-r0

apk add --upgrade apache2 apk info -v apache2

Alpine 3.22 · apache2 · FIXED · apache2-2.4.67-r0

apk add --upgrade apache2 apk info -v apache2

Alpine 3.23 · apache2 · FIXED · apache2-2.4.67-r0

apk add --upgrade apache2 apk info -v apache2

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-1720 · source

sudo dnf update --advisory=ALAS2023-2026-1720

Amazon Linux 2 · see advisory · FIXED · ALAS2-2026-3314 · source

sudo yum update --advisory=ALAS2-2026-3314

Advisories and coverage

Official advisories

AlmaLinux Errata: [ALSA-2026:21391] Important: httpd security update 2026-05-29

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-28780?

http server: upgrade to 2.4.67. Exact commands for each OS are on this page.

Is CVE-2026-28780 being exploited?

CVE-2026-28780 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-28780 affect?

CVE-2026-28780 affects http server. Severity is critical (CVSS 9.8). 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 con

How urgent is CVE-2026-28780?

Priority 65/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Apache HTTP Server vulnerabilities

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References

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