CVE-2026-5673 | Libtheora: libtheora: denial of service or information disclosure via malformed avi file processing

Exp

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.

Published: 2026-04-06 Last update: 2026-05-01 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-5673 is rated Exploit Available (50/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.18%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-5673

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-5673

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.01% 0.18% +0.17%
2 2026-04-06 — 0.01% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-5673

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.6 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.3 4.2 [email protected]
7.1 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 5.2 [email protected]

Weakness enumeration for CVE-2026-5673

OS Trackers for CVE-2026-5673

vendor priority summary link
debian not yet assigned CVE-2026-5673 not yet assigned priority: Debian including 1 source packages (libtheora), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 5. https://security-tracker.debian.org/tracker/CVE-2026-5673
redhat medium — https://access.redhat.com/security/cve/CVE-2026-5673
suse medium — https://www.suse.com/security/cve/CVE-2026-5673/
ubuntu medium CVE-2026-5673 medium priority: Ubuntu including 4 source packages (asc, libtheora, mkvtoolnix, ogmrip), 32 status rows across 8 suites (bionic, focal, jammy, noble, questing, resolute, upstream, xenial): deferred 20, not-affected 7, needs-triage 4, DNE 1. https://ubuntu.com/security/CVE-2026-5673

Affected software / configurations for CVE-2026-5673

Vendor Product Version Raw CPE
xiph theora — cpe:2.3:a:xiph:theora:-:*:*:*:*:*:*:*
redhat enterprise_linux 6.0 cpe:2.3:o:redhat:enterprise_linux:6.0:*:*:*:*:*:*:*
redhat enterprise_linux 7.0 cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
redhat enterprise_linux 8.0 cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
redhat enterprise_linux 9.0 cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*
redhat enterprise_linux 10.0 cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:*

References for CVE-2026-5673

URL Tags
https://access.redhat.com/security/cve/CVE-2026-5673 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2455340 Issue Tracking Third Party Advisory
https://github.com/xiph/theora/issues/24 Exploit Issue Tracking Third Party Advisory
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