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Fencer Intel
medium 5.6

CVE-2026-5673 json

Libtheora: libtheora: denial of service or information disclosure via malformed avi file processing

published 7mo ago modified 6d ago also EUVD-2026-19219

cvss
5.6
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits
0
none known

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 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.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-5673 updated cvss 5.6

libtheora: libtheora: Denial of Service or Information Disclosure via malformed AVI file processing

  • Red Hat Enterprise Linux 6 libtheora, theora-tools Red Hat Enterprise Linux 7 libtheora, theora-tools Red Hat Enterprise Linux 8 libtheora, theora-tools Red Hat Enterprise Linux 9 libtheora, theora-tools Red Hat Enterprise Linux 10 libtheora
    affected: workaround, no fix available “To mitigate this issue, users should avoid opening untrusted AVI files. Exercise caution when handling AVI files from unknown or suspicious sources.”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
7mo ago

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/xiph/theora/issues/24 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.6 CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:H
NVD 3.1 7.1 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H

Affected products

  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.