CVE-2024-56431Public exploitNetwork attack vector

Undefined behavior via invalid Huffman-tree shift

Published Dec 25, 2024 · Updated May 7, 2025

Undefined behavior in libtheora at commit 7180717 allows context-dependent attackers to trigger an invalid shift with crafted Theora data. In oc_huff_tree_unpack in huffdec.c, a derived Huffman code length is used in a left-shift expression without first excluding a negative count. The PoC only triggers an UndefinedBehaviorSanitizer diagnostic, and the published dispute states that production builds do not crash or exhibit a security impact.

CVSS severity9.8
Critical
EPSS probability1.85%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Undefined behavior in libtheora at commit 7180717 allows context-dependent attackers to trigger an invalid shift with crafted Theora data. In oc_huff_tree_unpack in huffdec.c, a derived Huffman code length is used in a left-shift expression without first excluding a negative count. The PoC only triggers an UndefinedBehaviorSanitizer diagnostic, and the published dispute states that production builds do not crash or exhibit a security impact.

The record

CVE
CVE-2024-56431
Published
Dec 25, 2024
Updated
May 7, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-863
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 25, 2024CVE publishedPublication date reported by the CVE source.
  2. May 7, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-863Incorrect Authorization

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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