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CVE-2026-5673

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

5.6 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
Low
User interaction
Required

What an attacker can affect

Confidentiality
Low
Integrity
None
Availability
High

Exploit likelihood

0.18%Up 0.2 points since Apr 6, 2026
90%50%10%1%

What each source reports

CVE List Score used 5.6

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

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.

Record
CVE-2026-5673
CVSS 3.1
5.6 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:H
Weakness
CWE-125
Updated
2026-11-02
EUVDEUVD-2026-19219 5.6

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.

Record
EUVD-2026-19219
CVSS 3.1
5.6 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-cjcp-vc46-rm2h 5.6

A flaw was found in libtheora. This heap-based out-of-bounds read vulnerability exists within the...

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.

Record
GHSA-cjcp-vc46-rm2h
CVSS 3.1
5.6 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:H
Weakness
CWE-125
Updated
2026-11-02
NVD 5.6

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.

Record
CVE-2026-5673
CVSS 3.1
5.6 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:H
CVSS 3.1
7.1 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H
Weakness
CWE-125
Updated
2026-11-02
OSVDEBIAN-CVE-2026-5673 7.1

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.

Record
DEBIAN-CVE-2026-5673
CVSS 3.1
7.1 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H
Updated
2026-11-02
OSVOESA-2026-2210 5.6

libtheora security update

Theora is a free and open video compression format from the Xiph.org Foundation. Like all our multimedia technology it can be used to distribute film and video online and on disc without the licensing and royalty fees or vendor lock-in associated with other formats.

Security Fix(es):

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.(CVE-2026-5673)

Record
OESA-2026-2210
CVSS 3.1
5.6 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:H
Updated
2026-11-02
OSVROOT-OS-DEBIAN-13-CVE-2026-5673 7.1

CVE-2026-5673 in libtheora - Patched by Root

Root has patched CVE-2026-5673 in the libtheora package for Root:Debian:13. Multiple fixed versions available.

Record
ROOT-OS-DEBIAN-13-CVE-2026-5673
CVSS 3.1
7.1 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2026-5673 5.6

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.

Record
UBUNTU-CVE-2026-5673
CVSS 3.1
5.6 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:H
CVSS 3.1
7.1 HighCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
libtheora
Debian:12
 All versions, plus listed versions
1.1.1+dfsg.1-16.11.1.1+dfsg.1-16.1+deb12u11.1.1+dfsg.1-171.2.0+dfsg-11.2.0+dfsg-2
Show 10 moreShow less
1.2.0+dfsg-31.2.0+dfsg-41.2.0+dfsg-51.2.0+dfsg-61.2.0~alpha1+dfsg-11.2.0~alpha1+dfsg-21.2.0~alpha1+dfsg-31.2.0~alpha1+dfsg-41.2.0~alpha1+dfsg-51.2.0~alpha1+dfsg-6
 None known
libtheora
Debian:13
 All versions, plus listed versions
1.2.0+dfsg-11.2.0+dfsg-21.2.0+dfsg-31.2.0+dfsg-41.2.0+dfsg-51.2.0+dfsg-61.2.0~alpha1+dfsg-6
 None known
libtheora
Debian:14
 All versions, plus listed versions
1.2.0+dfsg-11.2.0+dfsg-21.2.0+dfsg-31.2.0+dfsg-41.2.0+dfsg-51.2.0+dfsg-61.2.0~alpha1+dfsg-6
 None known
libtheora
openEuler:20.03-LTS-SP4
 before 1.1.1-26.oe2003sp4
1.1.1-26.oe2003sp4
libtheora
openEuler:22.03-LTS-SP4
 before 1.1.1-27.oe2203sp4
1.1.1-27.oe2203sp4
libtheora
openEuler:24.03-LTS
 before 1.1.1-29.oe2403sp3
1.1.1-29.oe2403sp3
libtheora
openEuler:24.03-LTS-SP1
 before 1.1.1-29.oe2403sp1
1.1.1-29.oe2403sp1
libtheora
openEuler:24.03-LTS-SP3
 before 1.1.1-29.oe2403sp3
1.1.1-29.oe2403sp3
libtheora
Root:Debian:13
 before 1.2.0~alpha1+dfsg-6.aikido.3
1.2.0~alpha1+dfsg-6.aikido.31.2.0~alpha1+dfsg-6.aikido.21.2.0~alpha1+dfsg-6.root.io.1
rootio-libtheora
Root:Debian:13
 before 1.2.0~alpha1+dfsg-6.aikido.3
1.2.0~alpha1+dfsg-6.aikido.31.2.0~alpha1+dfsg-6.aikido.21.2.0~alpha1+dfsg-6.root.io.1
Show 23 moreShow less
Affected packages
PackageAffectedFixed
asc
Ubuntu:16.04:LTS
 All versions, plus listed versions
2.6.0.0-1build12.6.1.0-1
 None known
mkvtoolnix
Ubuntu:16.04:LTS
 All versions, plus listed versions
8.2.0-28.5.1-18.5.2-18.6.0-18.6.1-18.7.0-18.8.0-1
 None known
ogmrip
Ubuntu:16.04:LTS
 All versions, plus listed versions
1.0.0-0ubuntu11.0.1-1
 None known
asc
Ubuntu:18.04:LTS
 All versions, plus listed versions
2.6.1.0-22.6.1.0-2build12.6.1.0-3
 None known
mkvtoolnix
Ubuntu:18.04:LTS
 All versions, plus listed versions
15.0.0-115.0.0-1build117.0.0-218.0.0-119.0.0-1
 None known
ogmrip
Ubuntu:18.04:LTS
 All versions, plus listed versions
1.0.1-1build2
 None known
asc
Ubuntu:20.04:LTS
 All versions, plus listed versions
2.6.1.0-5build12.6.1.0-62.6.1.0-6build12.6.1.0-6build22.6.1.0-6build32.6.1.0-6build4
 None known
mkvtoolnix
Ubuntu:20.04:LTS
 All versions, plus listed versions
37.0.0-1build138.0.0-139.0.0-140.0.0-140.0.0-3
Show 8 moreShow less
41.0.0-142.0.0-143.0.0-143.0.0-1ubuntu143.0.0-1ubuntu244.0.0-1ubuntu145.0.0-1ubuntu145.0.0-2
 None known
ogmrip
Ubuntu:20.04:LTS
 All versions, plus listed versions
1.0.1-1build21.0.1-21.0.1-2build11.0.1-3
 None known
asc
Ubuntu:22.04:LTS
 All versions, plus listed versions
2.6.1.0-7build32.6.1.0-82.6.1.0-8build1
 None known
mkvtoolnix
Ubuntu:22.04:LTS
 All versions, plus listed versions
60.0.0-262.0.0-1build163.0.0-164.0.0-165.0.0-1
 None known
ogmrip
Ubuntu:22.04:LTS
 All versions, plus listed versions
1.0.1-3.1
 None known
asc
Ubuntu:24.04:LTS
 All versions, plus listed versions
2.6.1.0-9build22.6.1.0-9build32.6.1.0-9build42.6.1.0-9build5
 None known
mkvtoolnix
Ubuntu:24.04:LTS
 All versions, plus listed versions
78.0-279.0-180.0-181.0-181.0-1build182.0-182.0-1build182.0-1build2
 None known
asc
Ubuntu:25.10
 All versions, plus listed versions
2.6.1.0-9build5
 None known
mkvtoolnix
Ubuntu:25.10
 All versions, plus listed versions
90.0-1build192.0-192.0-1build294.0-1
 None known
ogmrip
Ubuntu:25.10
 All versions, plus listed versions
1.0.1-51.0.1-5build1
 None known
asc
Ubuntu:26.10
 All versions, plus listed versions
2.6.1.0-9build6
 None known
mkvtoolnix
Ubuntu:26.10
 All versions, plus listed versions
97.0-1build198.0-199.0-1100.0-2
 None known
ogmrip
Ubuntu:26.10
 All versions, plus listed versions
1.0.1-5build2
 None known
asc
Ubuntu:26.04:LTS
 All versions, plus listed versions
2.6.1.0-9build52.6.1.0-9build6
 None known
mkvtoolnix
Ubuntu:26.04:LTS
 All versions, plus listed versions
94.0-195.0-196.0-197.0-197.0-1build1
 None known
ogmrip
Ubuntu:26.04:LTS
 All versions, plus listed versions
1.0.1-5build11.0.1-5build2
 None known

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-5673 is a medium vulnerability (CVSS 5.6) in Xiph Theora, published April 6, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.18%, the 7th percentile. Fixed in libtheora 1.1.1-26.oe2003sp4.

References

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