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CVE-2018-1312: In Apache httpd 2.2.0 to 2.4.29, when generating an HTTP Digest authentication challenge, the nonce sent to pr

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This week
CRITICAL 9.8REMOTEWATCHLISTDOWNGRADEMITIGATEMITIGATE

CVE-2018-1312 is a critical-severity flaw (CVSS 9.8) affecting http server, ubuntu linux, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In Apache httpd 2.2.0 to 2.4.29, when generating an HTTP Digest authentication challenge, the nonce sent to prevent reply attacks was not correctly generated using a pseudo-random seed. In a cluster of servers using a common Digest authentication configuration, HTTP requests could be replayed across servers by an attacker without detection.

Why this priority

  • Critical severity
  • EPSS top 3%: 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 score9.8 (Critical)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededNone
User interactionNone
EPSS exploit chance15.7% (top 3%)
CISA exploited listNo
WeaknessCWE-287
Published2018-03-26
Last modified2026-06-17
Publisher (CNA): Apache Software Foundation · Vendor: apache · canonical · debian · netapp

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

Am I affected?

Timeline

apache http server DOWNGRADE
Affected: 2.4.1 · 2.4.2 · 2.4.3 · 2.4.4 · 2.4.6 · 2.4.7 · 2.4.9 · 2.4.10
Fixed in: no fixed release known
Safe to downgrade to: a release before 2.4.1
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 2.4.1 (Debian / Ubuntu)
apt-cache madison http-server sudo apt install http-server=<VERSION_BEFORE_2.4.1> 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_2.4.1> 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.
canonical ubuntu linux MITIGATE
Affected: 12.04 · 14.04 · 16.04 · 17.10 · 18.04
Fixed in: no fixed release known
Safe to downgrade to: a release before 12.04
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: 7.0 · 8.0 · 9.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 7.0
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.
netapp cloud backup MITIGATE
Affected: all versions
Fixed in: no fixed release known
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy cloud-backup || rpm -q cloud-backup || cloud-backup --version
No fixed or unaffected release known
Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.
netapp storagegrid MITIGATE
Affected: all versions
Fixed in: no fixed release known
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy storagegrid || rpm -q storagegrid || storagegrid --version
No fixed or unaffected release known
Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.
netapp clustered data ontap MITIGATE
Affected: all versions
Fixed in: no fixed release known
Safe to downgrade to: no unaffected older release
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.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.
Fedora ELN · dropbear · FIXED · 2026.94-2.eln159 · FEDORA-2026-1f4bf22735 · source
sudo dnf upgrade --advisory=FEDORA-2026-1f4bf22735
Fedora 46 · python-odata-query · FIXED · 0.10.1-1.fc46 · FEDORA-2026-eab44dc513 · source
sudo dnf upgrade --advisory=FEDORA-2026-eab44dc513
Debian 12 · apache2 · FIXED · 2.4.33-1
sudo apt update && sudo apt install --only-upgrade apache2 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' apache2)" ge "2.4.33-1" && echo PATCHED || echo STILL-VULNERABLE
Debian 13 · apache2 · FIXED · 2.4.33-1
sudo apt update && sudo apt install --only-upgrade apache2 dpkg --compare-versions "$(dpkg-query -W -f='${Version}' apache2)" ge "2.4.33-1" && echo PATCHED || echo STILL-VULNERABLE
RHEL 7 · httpd · FIXED · httpd-2.4.6-89.el7_6.1
sudo dnf upgrade --advisory=RHSA-2019:1898 rpm -q httpd
RHEL 5 · httpd · DEFERRED
RHEL 6 · httpd · DEFERRED
RHEL 8 · httpd · NOT AFFECTED
Alpine 3.20 · apache2 · FIXED · apache2-2.4.33-r0
apk add --upgrade apache2 apk info -v apache2
Alpine 3.21 · apache2 · FIXED · apache2-2.4.33-r0
apk add --upgrade apache2 apk info -v apache2
Alpine 3.22 · apache2 · FIXED · apache2-2.4.33-r0
apk add --upgrade apache2 apk info -v apache2
Alpine 3.23 · apache2 · FIXED · apache2-2.4.33-r0
apk add --upgrade apache2 apk info -v apache2
Amazon Linux 1 · see advisory · FIXED · ALAS-2018-1004 · source
sudo yum update --advisory=ALAS-2018-1004
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-2018-1312?

http server: downgrade or apply the listed mitigation; ubuntu linux: 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-2018-1312 being exploited?

CVE-2018-1312 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-2018-1312 affect?

CVE-2018-1312 affects http server, ubuntu linux, debian linux. Severity is critical (CVSS 9.8). In Apache httpd 2.2.0 to 2.4.29, when generating an HTTP Digest authentication challenge, the nonce sent to prevent reply attacks was not correctly generated using a pseudo-random seed. In a cluster of servers using a common Digest authenti

How urgent is CVE-2018-1312?

Priority 69/100. Critical severity; EPSS top 3%: very likely to be exploited; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Apache HTTP Server vulnerabilities · Ubuntu vulnerabilities · Debian vulnerabilities

Related CVEs

References

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