CVE-2020-12460: OpenDMARC through 1.3.2 and 1.4.x through 1.4.0-Beta1 has improper null termination in the function opendmarc_

Q: How do I fix CVE-2020-12460?

opendmarc: upgrade to newer than 1.3.2; fedora: mitigate or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2020-12460 being exploited?

CVE-2020-12460 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-2020-12460 affect?

CVE-2020-12460 affects opendmarc, fedora, debian linux. Severity is critical (CVSS 9.8). OpenDMARC through 1.3.2 and 1.4.x through 1.4.0-Beta1 has improper null termination in the function opendmarc_xml_parse that can result in a one-byte heap overflow in opendmarc_xml when parsing a specially crafted DMARC aggregate report. Th

Q: How urgent is CVE-2020-12460?

Priority 72/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

This week

CRITICAL 9.8REMOTEWATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2020-12460 is a critical-severity flaw (CVSS 9.8) affecting opendmarc, fedora, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

OpenDMARC through 1.3.2 and 1.4.x through 1.4.0-Beta1 has improper null termination in the function opendmarc_xml_parse that can result in a one-byte heap overflow in opendmarc_xml when parsing a specially crafted DMARC aggregate report. This can cause remote memory corruption when a '\0' byte overwrites the heap metadata of the next chunk and its PREV_INUSE flag.

Why this priority

Critical severity
Public exploit reference
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	3.7% (top 10%)
CISA exploited list	No
Weakness	CWE-787
Published	2020-07-27
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian · fedoraproject · trusteddomain

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

Am I affected?

Timeline

2020-07-27 23:15 UTCPublished CVE record published
2026-06-17 02:51 UTCUpdated Record last modified

trusteddomain opendmarc UPGRADE

Affected: <= 1.3.2 · 1.4.0 beta0 · 1.4.0 beta1

Fixed in: newer than 1.3.2

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 1.3.2 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade opendmarc

Note

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

fedoraproject fedora MITIGATE

Affected: 33 · 34

Fixed in: no fixed release known

Safe to downgrade to: a release before 33

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.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora 46 · keepalived · FIXED · 2.4.3-1.fc46 · FEDORA-2026-0c83a077d7 · source

sudo dnf upgrade --advisory=FEDORA-2026-0c83a077d7

Fedora ELN · dracut · FIXED · 111-5.eln159 · FEDORA-2026-982407d9e3 · source

sudo dnf upgrade --advisory=FEDORA-2026-982407d9e3

Ubuntu 20.04 · opendmarc · FIXED · 1.3.2-7ubuntu0.1

sudo apt update && sudo apt install --only-upgrade opendmarc dpkg --compare-versions "$(dpkg-query -W -f='${Version}' opendmarc)" ge "1.3.2-7ubuntu0.1" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 22.04 · opendmarc · NOT AFFECTED

Debian 12 · opendmarc · FIXED · 1.4.0~beta1+dfsg-3

sudo apt update && sudo apt install --only-upgrade opendmarc dpkg --compare-versions "$(dpkg-query -W -f='${Version}' opendmarc)" ge "1.4.0~beta1+dfsg-3" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · opendmarc · FIXED · 1.4.0~beta1+dfsg-3

sudo apt update && sudo apt install --only-upgrade opendmarc dpkg --compare-versions "$(dpkg-query -W -f='${Version}' opendmarc)" ge "1.4.0~beta1+dfsg-3" && echo PATCHED || echo STILL-VULNERABLE

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: github.com/trusteddomainproject/OpenDMARC/issues/64
GitHub PoC: Live-Hack-CVE/CVE-2020-12460

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-2020-12460?

opendmarc: upgrade to newer than 1.3.2; 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-2020-12460 being exploited?

CVE-2020-12460 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-2020-12460 affect?

CVE-2020-12460 affects opendmarc, fedora, debian linux. Severity is critical (CVSS 9.8). OpenDMARC through 1.3.2 and 1.4.x through 1.4.0-Beta1 has improper null termination in the function opendmarc_xml_parse that can result in a one-byte heap overflow in opendmarc_xml when parsing a specially crafted DMARC aggregate report. Th

How urgent is CVE-2020-12460?

Priority 72/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities

Related CVEs

CVE-2024-25768 HIGH 7.5 DOWNGRADE OpenDMARC 1.4.2 contains a null pointer dereference vulnerability in /OpenDMARC/libopendmarc/opendmarc_policy.
CVE-2021-34555 HIGH 7.5 DOWNGRADE MITIGATE OpenDMARC 1.4.1 and 1.4.1.1 allows remote attackers to cause a denial of service (NULL pointer dereference and
CVE-2020-12272 MEDIUM 5.3 UPGRADE MITIGATE OpenDMARC through 1.3.2 and 1.4.x allows attacks that inject authentication results to provide false informati
CVE-2019-20790 CRITICAL 9.8 UPGRADE DOWNGRADE OpenDMARC through 1.3.2 and 1.4.x, when used with pypolicyd-spf 2.0.2, allows attacks that bypass SPF and DMAR

References

← Back to latest CVEs