VulnerabilityPublished 31 Mar 2026

CVE-2026-5235: Axiomatic Bento4 · Heap-based Buffer Overflow

Affects Axiomatic Bento4Source CVE Database V5

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Public exploit available · CVSS 4.8 Medium.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 4.0 base score

4.8Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P

Base metrics

Attack Vector: Local
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: None
Vulnerable system confidentiality: Low
Vulnerable system integrity: Low
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Threat metrics

Exploit Maturity: POC

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable system is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Vulnerable System.
Vulnerable system integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Vulnerable System.
Vulnerable system availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.
Exploit Maturity: POC: Based on threat intelligence sources each of the following must apply: · Proof-of-concept is publicly available · No knowledge of reported attempts to exploit this vulnerability · No knowledge of publicly available solutions used to simplify attempts to exploit the vulnerability

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 31 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
CVSS exploit maturity: proof of concept public
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CVSS vector, the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
AxiomaticBento4	Affected =1.6.0-641	Fixed in–
GitHubaxiomatic-systems/Bento4`pkg:github/axiomatic-systems/Bento4`Other threats	Affected =1.6.0-641	Fixed in–

CPE configurations (1)

cpe:2.3:a:bento4:bento4:*:*:*:*:*:*:*:*

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AI-suggested

Given the absence of an official patch, organizations should implement several specific mitigations: 1) Restrict local access to systems running Bento4 to trusted users only, minimizing the risk of local exploitation. 2) Employ application sandboxing or containerization to limit the impact of potential exploitation by isolating Bento4 processes. 3) Monitor and audit usage of Bento4, especially when parsing untrusted MP4 files, to detect abnormal behavior or crashes indicative of exploitation attempts. 4) Consider replacing or upgrading Bento4 to a version beyond 1.6.0-641 once a patch is available or using alternative MP4 parsing libraries with no known vulnerabilities. 5) Implement strict input validation and file integrity checks upstream to reduce the likelihood of processing malicious MP4 files. 6) Use operating system-level protections such as Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR) to mitigate exploitation success. 7) Maintain up-to-date backups and incident response plans to quickly recover from potential compromises. These targeted measures go beyond generic advice by focusing on access control, process isolation, and proactive monitoring specific to the nature of this vulnerability.

Description

A vulnerability was determined in Axiomatic Bento4 up to 1.6.0-641. This impacts the function AP4_BitReader::ReadCache of the file Ap4Dac4Atom.cpp of the component MP4 File Parser. This manipulation causes heap-based buffer overflow. The attack needs to be launched locally. The exploit has been publicly disclosed and may be utilized. The project was informed of the problem early through an issue report but has not responded yet.

Impact

The heap-based buffer overflow in Bento4 can lead to memory corruption, causing application instability or crashes, which affects availability. More critically, if exploited successfully, it could allow an attacker to execute arbitrary code with the privileges of the affected application, compromising confidentiality and integrity. Since exploitation requires local access with low privileges, the threat is mainly to environments where untrusted users have local system access or where Bento4 is used in multi-user or shared environments. This could include media servers, content delivery networks, or developer workstations processing untrusted MP4 files. The lack of a patch increases exposure time, and public disclosure may lead to increased exploitation attempts. Organizations relying on Bento4 for media parsing or processing could face service disruptions or unauthorized code execution, potentially leading to broader system compromise if the vulnerable component runs with elevated privileges.

Summary

CVE-2026-5235 is a heap-based buffer overflow vulnerability found in the Axiomatic Bento4 library, a widely used open-source MP4 file parser and toolkit. The flaw resides in the AP4_BitReader::ReadCache function within the Ap4Dac4Atom.cpp source file. This function improperly handles memory operations, allowing an attacker with local access and low privileges to manipulate input data in a way that causes a buffer overflow on the heap. Such a condition can corrupt memory, potentially leading to application crashes or enabling an attacker to execute arbitrary code within the context of the vulnerable process. The vulnerability affects Bento4 versions up to 1.6.0-641. Exploitation requires local access, no user interaction, and low attack complexity, but privileges are required. The CVSS v4.0 base score is 4.8, reflecting medium severity due to the local attack vector and limited scope. No known exploits have been observed in the wild yet, but public disclosure increases the risk of exploitation attempts. Bento4 is commonly integrated into media processing pipelines, video streaming platforms, and multimedia applications, making this vulnerability relevant to organizations handling MP4 content processing.

References

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