---
id: CVE-2026-5673
title: >-
  Libtheora: libtheora: denial of service or information disclosure via
  malformed avi file processing
summary: >-
  A flaw was found in libtheora. This heap-based out-of-bounds read
  vulnerability exists within the AVI (Audio Video Interleave) parser,
  specifically in the avi_parse_input_file() function. A local attacker could
  exploit this by tricking a…
severity: medium
cvss: 5.6
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-125
vendor: Red Hat
product: libtheora
affected:
  - libtheora (all versions)
  - libtheora (all versions)
  - libtheora (all versions)
  - libtheora (all versions)
  - libtheora (all versions)
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-04-06T17:50:45.440733Z'
published: '2026-04-06'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T21:43:01.911Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-5673'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-5673'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2455340'
    label: RHBZ#2455340
  - url: 'https://github.com/xiph/theora/issues/24'
tags:
  - cve.org
epss: 0.00181
epssPercentile: 0.0773
ingestedAt: '2026-11-05T22:38:32.141Z'
---

## Overview

A flaw was found in libtheora. This heap-based out-of-bounds read vulnerability exists within the AVI (Audio Video Interleave) parser, specifically in the avi_parse_input_file() function. A local attacker could exploit this by tricking a user into opening a specially crafted AVI file containing a truncated header sub-chunk. This could lead to a denial-of-service (application crash) or potentially leak sensitive information from the heap.

## Affected

- `libtheora (all versions)`
- `libtheora (all versions)`
- `libtheora (all versions)`
- `libtheora (all versions)`
- `libtheora (all versions)`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

### Workarounds

To mitigate this issue, users should avoid opening untrusted AVI files. Exercise caution when handling AVI files from unknown or suspicious sources.