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Unrated severityNVD Advisory· Published Mar 3, 2021· Updated Aug 4, 2024

CVE-2020-25632

CVE-2020-25632

Description

A use-after-free flaw in grub2's rmmod command allows arbitrary code execution or Secure Boot bypass, affecting versions prior to 2.06.

AI Insight

LLM-synthesized narrative grounded in this CVE's description and references.

A use-after-free flaw in grub2's rmmod command allows arbitrary code execution or Secure Boot bypass, affecting versions prior to 2.06.

Vulnerability

The rmmod implementation in grub2 versions prior to 2.06 is flawed, allowing the unloading of a module that is still a dependency for other loaded modules without proper checks. This leads to a use-after-free condition [1]. The bug resides in the module unloading code path and is reachable when the rmmod command is executed on a module that is a dependency.

Exploitation

An attacker with the ability to execute the rmmod command (e.g., local access to the GRUB shell or via a compromised boot configuration) can trigger the vulnerability. By unloading a module that is a dependency, the attacker causes use-after-free, potentially leveraging memory corruption to execute arbitrary code. No authentication is required beyond access to GRUB's command line.

Impact

Successful exploitation could allow arbitrary code execution within the GRUB environment, bypassing Secure Boot protections. This compromises data confidentiality, integrity, and system availability, as the attacker can run arbitrary code at boot time [3].

Mitigation

The vulnerability is fixed in grub2 version 2.06 and later. Red Hat has issued patches for various RHEL versions via RHSA-2021:0702 [1]. Gentoo recommends upgrading to >=sys-devel/grub-2.06_rc1 and re-running grub-install [3]. No workaround is available; users should apply the update.

References
  1. 1879577 – (CVE-2020-25632) CVE-2020-25632 grub2: Use-after-free in rmmod command
  2. Multiple vulnerabilities (GLSA 202104-05) — Gentoo security

AI Insight generated on May 26, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.

Affected products

41

Patches

0

No patches discovered yet.

Vulnerability mechanics

No source-code context for this CVE — mechanics is only generated when we can read the actual fix diff. Without that, the four sections (root cause, attack vector, affected code, fix) would be speculation rather than analysis.

References

4

News mentions

0

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