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CVE-2021-47638

7.8 · HIGH

In the Linux kernel, the following vulnerability has been resolved: ubifs: rename_whiteout: Fix double free for whiteout_ui->data 'whiteout_ui->data' will be freed twice if space budget fail for…

Published Feb 26, 2025CWE-415EPSS 0.26%

Overview

CVE-2021-47638 is a high-severity vulnerability. It was published on February 26, 2025 and has a CVSS 3.1 base score of 7.8 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical description

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

ubifs: rename_whiteout: Fix double free for whiteout_ui->data

'whiteout_ui->data' will be freed twice if space budget fail for

rename whiteout operation as following process:

rename_whiteout

dev = kmalloc

whiteout_ui->data = dev

kfree(whiteout_ui->data) // Free first time

iput(whiteout)

ubifs_free_inode

kfree(ui->data) // Double free!

KASAN reports:

==================================================================

BUG: KASAN: double-free or invalid-free in ubifs_free_inode+0x4f/0x70

Call Trace:

kfree+0x117/0x490

ubifs_free_inode+0x4f/0x70 [ubifs]

i_callback+0x30/0x60

rcu_do_batch+0x366/0xac0

__do_softirq+0x133/0x57f

Allocated by task 1506:

kmem_cache_alloc_trace+0x3c2/0x7a0

do_rename+0x9b7/0x1150 [ubifs]

ubifs_rename+0x106/0x1f0 [ubifs]

do_syscall_64+0x35/0x80

Freed by task 1506:

kfree+0x117/0x490

do_rename.cold+0x53/0x8a [ubifs]

ubifs_rename+0x106/0x1f0 [ubifs]

d

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/14276d38c89a170363e90b6ac0a53c3cf61b87fcRefgit.kernel.org/stable/c/2ad07009c459e56ebdcc089d850d664660fdb742Refgit.kernel.org/stable/c/2b3236ecf96db7af5836e1366ce39ace8ce832faRefgit.kernel.org/stable/c/40a8f0d5e7b3999f096570edab71c345da812e3eRefgit.kernel.org/stable/c/6d7a158a7363c1f6604aa47ae1a280a5c65123ddRefgit.kernel.org/stable/c/8b3c7be16f3f4dfd6e15ac651484e59d3fa36274Refgit.kernel.org/stable/c/a90e2dbe66d2647ff95a0442ad2e86482d977fd8Refgit.kernel.org/stable/c/b9a937f096e608b3368c1abc920d4d640ba2c94f

How CyberStrike helps

Frequently asked questions

What is CVE-2021-47638?

CVE-2021-47638 is a high-severity vulnerability. It was published on February 26, 2025 and has a CVSS 3.1 base score of 7.8 (HIGH).

How severe is CVE-2021-47638?

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2021-47638?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-47638?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-47638 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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