CVE-2022-23943: Out-of-bounds Write vulnerability in mod_sed of Apache HTTP Server allows an attacker to overwrite heap memory

This week

CRITICAL 9.8REMOTEWATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2022-23943 is a critical-severity flaw (CVSS 9.8) affecting http server, fedora, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Out-of-bounds Write vulnerability in mod_sed of Apache HTTP Server allows an attacker to overwrite heap memory with possibly attacker provided data. This issue affects Apache HTTP Server 2.4 version 2.4.52 and prior versions.

Why this priority

Critical severity
EPSS top 1%: very likely to be exploited
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	50.4% (top 1%)
CISA exploited list	No
Weakness	CWE-190, CWE-787
Published	2022-03-14
Last modified	2026-06-17

Publisher (CNA): Apache Software Foundation · Vendor: apache · debian · fedoraproject · oracle

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2022-03-14 11:15 UTCPublished CVE record published
2026-06-17 04:31 UTCUpdated Record last modified

apache http server UPGRADE

Affected: >= 2.4.0 and < 2.4.53

Fixed in: 2.4.53

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 2.4.53 (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.

fedoraproject fedora MITIGATE

Affected: 34 · 35 · 36

Fixed in: no fixed release known

Safe to downgrade to: a release before 34

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

debian debian linux MITIGATE

Affected: 9.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 9.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

oracle http server DOWNGRADE

Affected: 12.2.1.3.0 · 12.2.1.4.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 12.2.1.3.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 12.2.1.3.0 (Debian / Ubuntu)

apt-cache madison http-server sudo apt install http-server=<VERSION_BEFORE_12.2.1.3.0> sudo apt-mark hold http-server

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list http-server sudo dnf downgrade http-server-<VERSION_BEFORE_12.2.1.3.0> 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.

oracle zfs storage appliance kit DOWNGRADE

Affected: 8.8

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.8

1. Check installed version

apt-cache policy zfs-storage-appliance-kit || rpm -q zfs-storage-appliance-kit || zfs-storage-appliance-kit --version

2. No fixed release: DOWNGRADE to a release before 8.8 (Debian / Ubuntu)

apt-cache madison zfs-storage-appliance-kit sudo apt install zfs-storage-appliance-kit=<VERSION_BEFORE_8.8> sudo apt-mark hold zfs-storage-appliance-kit

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list zfs-storage-appliance-kit sudo dnf downgrade zfs-storage-appliance-kit-<VERSION_BEFORE_8.8> sudo dnf versionlock add zfs-storage-appliance-kit

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

A distro patch exists: prefer upgrading over downgrading.

Fedora 46 · nodejs-pnpm12 · FIXED · 12.17.0-1.fc46 · FEDORA-2026-7adfb2bcdd · source

sudo dnf upgrade --advisory=FEDORA-2026-7adfb2bcdd

Fedora ELN · wget2 · FIXED · 2.3.0-3.eln159 · FEDORA-2026-811b4922a5 · source

sudo dnf upgrade --advisory=FEDORA-2026-811b4922a5

Ubuntu 22.04 · apache2 · FIXED · 2.4.52-1ubuntu2

sudo apt update && sudo apt install --only-upgrade apache2 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' apache2)" ge "2.4.52-1ubuntu2" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 20.04 · apache2 · FIXED · 2.4.41-4ubuntu3.10

sudo apt update && sudo apt install --only-upgrade apache2 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' apache2)" ge "2.4.41-4ubuntu3.10" && echo PATCHED || echo STILL-VULNERABLE

Debian 12 · apache2 · FIXED · 2.4.53-1

sudo apt update && sudo apt install --only-upgrade apache2 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' apache2)" ge "2.4.53-1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · apache2 · FIXED · 2.4.53-1

sudo apt update && sudo apt install --only-upgrade apache2 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' apache2)" ge "2.4.53-1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 9 · httpd · FIXED · httpd-2.4.53-7.el9

sudo dnf upgrade --advisory=RHSA-2022:8067 rpm -q httpd

RHEL 6 · httpd · NOT AFFECTED

RHEL 7 · httpd · DEFERRED

Alpine 3.20 · apache2 · FIXED · apache2-2.4.53-r0

apk add --upgrade apache2 apk info -v apache2

Alpine 3.21 · apache2 · FIXED · apache2-2.4.53-r0

apk add --upgrade apache2 apk info -v apache2

Alpine 3.22 · apache2 · FIXED · apache2-2.4.53-r0

apk add --upgrade apache2 apk info -v apache2

Alpine 3.23 · apache2 · FIXED · apache2-2.4.53-r0

apk add --upgrade apache2 apk info -v apache2

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2023-072 · source

sudo dnf update --advisory=ALAS2023-2023-072

Amazon Linux 2 · see advisory · FIXED · ALAS2-2022-1783 · source

sudo yum update --advisory=ALAS2-2022-1783

Amazon Linux 1 · see advisory · FIXED · ALAS-2022-1584 · source

sudo yum update --advisory=ALAS-2022-1584

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: www.oracle.com/security-alerts/cpuapr2022.html

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-2022-23943?

http server: upgrade to 2.4.53; fedora: mitigate or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2022-23943 being exploited?

CVE-2022-23943 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-2022-23943 affect?

CVE-2022-23943 affects http server, fedora, debian linux. Severity is critical (CVSS 9.8). Out-of-bounds Write vulnerability in mod_sed of Apache HTTP Server allows an attacker to overwrite heap memory with possibly attacker provided data. This issue affects Apache HTTP Server 2.4 version 2.4.52 and prior versions.

How urgent is CVE-2022-23943?

Priority 69/100. Critical severity; EPSS top 1%: very likely to be exploited; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Apache HTTP Server vulnerabilities · Debian vulnerabilities

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References

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