CVE-2023-31137: MaraDNS is open-source software that implements the Domain Name System (DNS)

This month

HIGH 7.5REMOTEWATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2023-31137 is a high-severity flaw (CVSS 7.5) affecting maradns, fedora, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

MaraDNS is open-source software that implements the Domain Name System (DNS). In version 3.5.0024 and prior, a remotely exploitable integer underflow vulnerability in the DNS packet decompression function allows an attacker to cause a Denial of Service by triggering an abnormal program termination. The vulnerability exists in the `decomp_get_rddata` function within the `Decompress.c` file. When handling a DNS packet with an Answer RR of qtype 16

Why this priority

High severity
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.1% (top 33%)
CISA exploited list	No
Weakness	CWE-191
Published	2023-05-09
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: debian · fedoraproject · maradns

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

Am I affected?

Timeline

2023-05-09 14:15 UTCPublished CVE record published
2026-06-17 05:56 UTCUpdated Record last modified

maradns maradns UPGRADE

Affected: < 3.4.10 · >= 3.5.0001 and < 3.5.0036

Fixed in: 3.4.10, 3.5.0036

Safe to downgrade to: a release before 3.5.0001

1. Check installed version

apt-cache policy maradns || rpm -q maradns || maradns --version

2. UPGRADE to 3.4.10 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade maradns

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade maradns

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 3.5.0001 (Debian / Ubuntu)

apt-cache madison maradns sudo apt install maradns=<VERSION_BEFORE_3.5.0001> sudo apt-mark hold maradns

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list maradns sudo dnf downgrade maradns-<VERSION_BEFORE_3.5.0001> sudo dnf versionlock add maradns

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: 37 · 38

Fixed in: no fixed release known

Safe to downgrade to: a release before 37

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: 10.0 · 11.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.0

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.

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-2023-31137?

maradns: upgrade to 3.4.10, 3.5.0036; 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-2023-31137 being exploited?

CVE-2023-31137 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-2023-31137 affect?

CVE-2023-31137 affects maradns, fedora, debian linux. Severity is high (CVSS 7.5). MaraDNS is open-source software that implements the Domain Name System (DNS). In version 3.5.0024 and prior, a remotely exploitable integer underflow vulnerability in the DNS packet decompression function allows an attacker to cause a Denia

How urgent is CVE-2023-31137?

Priority 53/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities

Related CVEs

CVE-2022-30256 HIGH 7.5 UPGRADE An issue was discovered in MaraDNS Deadwood through 3.5.0021 that allows variant V1 of unintended domain name

References

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