What is the CVSS score of CVE-2021-47254?

CVE-2021-47254 has a CVSS 3.1 base score of 7.8 (High). CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

Which versions of Linux are affected by CVE-2021-47254?

CVE-2021-47254 presents notable security risk, a use-after-free vulnerability rated CVSS 7.8. Exploitation could compromise the security of affected deployments.. A patch is available.

How to fix or mitigate CVE-2021-47254?

Within 7 days: Identify all affected systems and apply vendor patches promptly. If patching is delayed, consider network segmentation to limit exposure.

Linux CVE-2021-47254

HIGH

Use After Free (CWE-416)

2024-05-21 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Information Disclosure Linux Use After Free Memory Corruption

7.8

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

7.8 HIGH

AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Mar 17, 2026 - 20:45 vuln.today

Patch released

Mar 17, 2026 - 20:45 nvd

Patch available

CVE Published

May 21, 2024 - 15:15 nvd

HIGH 7.8

DescriptionNVD

In the Linux kernel, the following vulnerability has been resolved:

gfs2: Fix use-after-free in gfs2_glock_shrink_scan

The GLF_LRU flag is checked under lru_lock in gfs2_glock_remove_from_lru() to remove the glock from the lru list in __gfs2_glock_put().

On the shrink scan path, the same flag is cleared under lru_lock but because of cond_resched_lock(&lru_lock) in gfs2_dispose_glock_lru(), progress on the put side can be made without deleting the glock from the lru list.

Keep GLF_LRU across the race window opened by cond_resched_lock(&lru_lock) to ensure correct behavior on both sides - clear GLF_LRU after list_del under lru_lock.

AnalysisAI

A use-after-free vulnerability exists in the GFS2 filesystem implementation of the Linux kernel, specifically in the gfs2_glock_shrink_scan function. The vulnerability affects multiple Linux kernel versions ranging from 4.4 through 5.13-rc2, allowing local attackers with low privileges to potentially achieve arbitrary code execution, information disclosure, or system crashes. With an EPSS score of only 0.02%, this vulnerability has a very low probability of real-world exploitation despite its high CVSS score of 7.8.

Technical ContextAI

The vulnerability occurs in the Global File System 2 (GFS2) distributed filesystem implementation, specifically in the glock (global lock) management subsystem. The issue stems from improper synchronization when handling the GLF_LRU flag during concurrent operations between gfs2_glock_remove_from_lru() and gfs2_dispose_glock_lru(). The cond_resched_lock() call creates a race window where the glock can be freed while still being referenced on the LRU list. This is classified as CWE-416 (Use After Free), a memory corruption vulnerability class where memory is accessed after being deallocated. Based on the CPE data, the vulnerability affects Linux kernel versions 4.4.x through 4.19.x, 5.4.x through 5.12.x, and 5.13 release candidates 1 and 2.

RemediationAI

Update the Linux kernel to a patched version that includes the fix commits referenced in the advisory. For kernel 5.13, apply commit 1ab19c5de4c537ec0d9b21020395a5b5a6c059b2 or later. For stable branches, apply the appropriate backported fixes: 5.12.x (38ce329534500bf4ae71f81df6a37a406cf187b4), 5.10.x (e87ef30fe73e7e10d2c85bdcc778dcec24dca553), 5.4.x (a61156314b66456ab6a291ed5deba1ebd002ab3c), 4.19.x (86fd5b27db743a0ce0cc245e3a34813b2aa6ec1d), 4.14.x (92869945cc5b78ee8a1ef90336fe070893e3458a), 4.9.x (094bf5670e762afa243d2c41a5c4ab71c7447bf4), and 4.4.x (0364742decb0f02bc183404868b82896f7992595). If immediate patching is not possible, consider disabling or unloading the GFS2 module if not required for production operations.