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

CVE-2021-20233

CVE-2021-20233

Description

A heap buffer overflow in GRUB2's menu rendering code due to miscalculation of quoted single quote length allows memory corruption, threatening confidentiality, integrity, and availability.

AI Insight

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

A heap buffer overflow in GRUB2's menu rendering code due to miscalculation of quoted single quote length allows memory corruption, threatening confidentiality, integrity, and availability.

Vulnerability

The vulnerability resides in the setparam_prefix() function in GRUB2's menu rendering code, affecting versions prior to 2.06. The function miscalculates the length required when quoting a single quote: it assumes 3 characters but actually needs 4. This results in a heap buffer overflow by one byte for each quote in the input [1].

Exploitation

An attacker can provide crafted input containing single quotes to trigger the miscalculation and corrupt memory. The attacker may not need authentication if they can influence the boot menu parameters, but the exact prerequisites depend on the system's configuration. The corruption is limited to one byte per quote, but repeated quotes could lead to more significant memory corruption.

Impact

Successful exploitation allows an attacker to corrupt memory, potentially leading to disclosure of sensitive data, integrity compromise, or denial of service. The highest threat is to data confidentiality and integrity as well as system availability [1].

Mitigation

The issue is fixed in GRUB2 version 2.06 [3]. For Red Hat Enterprise Linux 7.4 Advanced Update Support and similar, updates are available via RHSA-2021:0702 [1]. Gentoo users should upgrade to >=sys-devel/grub-2.06_rc1 [3]. No workaround is known [3].

References
  1. Heap out-of-bounds write due to miscalculation of space required for quoting
  2. Multiple vulnerabilities (GLSA 202104-05) — Gentoo security

AI Insight generated on May 27, 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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