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Unrated severityNVD Advisory· Published Jul 31, 2020· Updated Aug 4, 2024

CVE-2020-14311

CVE-2020-14311

Description

Grub2 before 2.06 has a heap-based buffer overflow in ext filesystem symlink handling due to arithmetic overflow on inode size, allowing local code execution and Secure Boot bypass.

AI Insight

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

Grub2 before 2.06 has a heap-based buffer overflow in ext filesystem symlink handling due to arithmetic overflow on inode size, allowing local code execution and Secure Boot bypass.

Vulnerability

The GRUB2 bootloader before version 2.06 contains a vulnerability in the handling of symbolic links on ext filesystems. When a filesystem provides a symbolic link with an inode size equal to UINT32_MAX, an arithmetic overflow occurs during memory allocation, resulting in a zero-sized allocation. This leads to a heap-based buffer overflow when data is written into the undersized buffer [2].

Exploitation

An attacker with local access to the system can exploit this by crafting a malicious ext filesystem containing a symbolic link with a manipulated inode size. The attacker must have the ability to boot the system or load the malicious filesystem, potentially via removable media or a compromised partition. The overflow occurs during GRUB2's filesystem traversal, prior to operating system boot.

Impact

Successful exploitation allows an attacker to execute arbitrary code within the context of the GRUB2 environment. This can lead to bypass of UEFI Secure Boot restrictions, as GRUB2 runs before the operating system and is responsible for validating boot components. The attacker gains the ability to load unsigned or malicious bootloaders or kernels, compromising the entire system boot chain.

Mitigation

The vulnerability is fixed in GRUB2 version 2.06 [2]. Users should update their GRUB2 package to version 2.06 or later. For Ubuntu systems, the fix is included in USN-4432-1 [2]. No workarounds are available other than applying the patch. Check vendor advisories for distribution-specific updates.

References
  1. USN-4432-1: GRUB 2 vulnerabilities | Ubuntu security notices | Ubuntu

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

30

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

8

News mentions

0

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