CVE-2024-56431: oc_huff_tree_unpack in huffdec.c in libtheora in Theora through 1.0 7180717 has an invalid negative left shift

Q: How do I fix CVE-2024-56431?

theora: upgrade to 1.2.0. Exact commands for each OS are on this page.

Q: Is CVE-2024-56431 being exploited?

CVE-2024-56431 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-2024-56431 affect?

CVE-2024-56431 affects theora. Severity is critical (CVSS 9.8). oc_huff_tree_unpack in huffdec.c in libtheora in Theora through 1.0 7180717 has an invalid negative left shift. NOTE: this is disputed by third parties because there is no evidence of a security impact, e.g., an application would not crash.

Q: How urgent is CVE-2024-56431?

Priority 67/100. Critical severity; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

This week

CRITICAL 9.8REMOTEUPGRADE

CVE-2024-56431 is a critical-severity flaw (CVSS 9.8) affecting theora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

oc_huff_tree_unpack in huffdec.c in libtheora in Theora through 1.0 7180717 has an invalid negative left shift. NOTE: this is disputed by third parties because there is no evidence of a security impact, e.g., an application would not crash.

Why this priority

Critical severity
Public exploit reference
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

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	1.8% (top 21%)
CISA exploited list	No
Weakness	CWE-863
Published	2024-12-25
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: xiph

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

Am I affected?

Timeline

2024-12-25 17:15 UTCPublished CVE record published
2026-06-17 08:12 UTCUpdated Record last modified

xiph theora UPGRADE

Affected: < 1.2.0

Fixed in: 1.2.0

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 1.2.0 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade theora

Note

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

Exact fixes by distribution

Fedora 46 · byobu · FIXED · 7.23-1.fc46 · FEDORA-2026-08f2b53446 · source

sudo dnf upgrade --advisory=FEDORA-2026-08f2b53446

Ubuntu 20.04 · libtheora · NOT AFFECTED

Ubuntu 22.04 · libtheora · NOT AFFECTED

Ubuntu 24.04 · libtheora · NOT AFFECTED

Ubuntu 24.10 · libtheora · NOT AFFECTED

Ubuntu 25.04 · libtheora · NOT AFFECTED

Debian 12 · libtheora · NOT AFFECTED

Debian 13 · libtheora · FIXED · 1.2.0~alpha1+dfsg-6

sudo apt update && sudo apt install --only-upgrade libtheora dpkg --compare-versions "$(dpkg-query -W -f='${Version}' libtheora)" ge "1.2.0~alpha1+dfsg-6" && echo PATCHED || echo STILL-VULNERABLE

RHEL 10 · libtheora · DEFERRED

RHEL 6 · libtheora · DEFERRED

RHEL 7 · firefox · DEFERRED

RHEL 7 · libtheora · DEFERRED

RHEL 7 · thunderbird · DEFERRED

Amazon Linux 2 · see advisory · FIXED · ALAS2-2025-2830 · source

sudo yum update --advisory=ALAS2-2025-2830

Public exploits and detection

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

GitHub PoC: UnionTech-Software/libtheora-CVE-2024-56431-PoC (1 stars)
Write-up: www.openwall.com/lists/oss-security/2025/04/25/6

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-2024-56431?

theora: upgrade to 1.2.0. Exact commands for each OS are on this page.

Is CVE-2024-56431 being exploited?

CVE-2024-56431 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-2024-56431 affect?

CVE-2024-56431 affects theora. Severity is critical (CVSS 9.8). oc_huff_tree_unpack in huffdec.c in libtheora in Theora through 1.0 7180717 has an invalid negative left shift. NOTE: this is disputed by third parties because there is no evidence of a security impact, e.g., an application would not crash.

How urgent is CVE-2024-56431?

Priority 67/100. Critical severity; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-5673 MEDIUM 5.6 MITIGATE MITIGATE A flaw was found in libtheora

References

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