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CVE-2026-44631: Buffer Underwrite vulnerability in Apache HTTP Server on crafted regular expressions in the configuration. Th

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CRITICAL 9.8REMOTEWATCHLISTUPGRADE

CVE-2026-44631 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.

Buffer Underwrite vulnerability in Apache HTTP Server on crafted regular expressions in the configuration. This issue affects Apache HTTP Server: from 2.4.0 through 2.4.67. Users are recommended to upgrade to version 2.4.68, 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 score9.8 (Critical)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededNone
User interactionNone
EPSS exploit chance0.5% (top 57%)
CISA exploited listNo
WeaknessCWE-124
Published2026-06-08
Last modified2026-07-23
Publisher (CNA): Apache Software Foundation · Vendor: apache

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Last updated 2026-07-23 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

apache http server UPGRADE
Affected: >= 2.4.0 and < 2.4.68
Fixed in: 2.4.68
Safe to downgrade to: a release before 2.4.0
1. Check installed version
apt-cache policy http-server || rpm -q http-server || http-server --version
2. UPGRADE to 2.4.68 (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.
3. If no update is available yet, DOWNGRADE to a release before 2.4.0 (Debian / Ubuntu)
apt-cache madison http-server sudo apt install http-server=<VERSION_BEFORE_2.4.0> sudo apt-mark hold http-server
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list http-server sudo dnf downgrade http-server-<VERSION_BEFORE_2.4.0> sudo dnf versionlock add http-server
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

Fedora 46 · arm-none-eabi-binutils-cs · FIXED · 2.47-1.fc46 · FEDORA-2026-7498616952 · source
sudo dnf upgrade --advisory=FEDORA-2026-7498616952
Debian 12 · apache2 · FIXED · 2.4.68-1~deb12u1
sudo apt update && sudo apt install --only-upgrade apache2 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' apache2)" ge "2.4.68-1~deb12u1" && echo PATCHED || echo STILL-VULNERABLE
Debian 13 · apache2 · FIXED · 2.4.68-1~deb13u1
sudo apt update && sudo apt install --only-upgrade apache2 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' apache2)" ge "2.4.68-1~deb13u1" && echo PATCHED || echo STILL-VULNERABLE
RHEL 10 · httpd · FIXED · httpd-2.4.63-13.el10_2.4
sudo dnf upgrade --advisory=RHSA-2026:34109 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_8.5
sudo dnf upgrade --advisory=RHSA-2026:41906 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 3.21 · apache2 · FIXED · apache2-2.4.68-r0
apk add --upgrade apache2 apk info -v apache2
Alpine 3.22 · apache2 · FIXED · apache2-2.4.68-r0
apk add --upgrade apache2 apk info -v apache2
Alpine 3.23 · apache2 · FIXED · apache2-2.4.68-r0
apk add --upgrade apache2 apk info -v apache2
Alpine 3.24 · apache2 · FIXED · apache2-2.4.68-r0
apk add --upgrade apache2 apk info -v apache2
Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-1880 · source
sudo dnf update --advisory=ALAS2023-2026-1880
Amazon Linux 2 · see advisory · FIXED · ALAS2-2026-3379 · source
sudo yum update --advisory=ALAS2-2026-3379
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-2026-44631?

http server: upgrade to 2.4.68. Exact commands for each OS are on this page.

Is CVE-2026-44631 being exploited?

CVE-2026-44631 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-2026-44631 affect?

CVE-2026-44631 affects http server. Severity is critical (CVSS 9.8). Buffer Underwrite vulnerability in Apache HTTP Server on crafted regular expressions in the configuration. This issue affects Apache HTTP Server: from 2.4.0 through 2.4.67. Users are recommended to upgrade to version 2.4.68, which fixes t

How urgent is CVE-2026-44631?

Priority 58/100. 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

Related CVEs

References

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