CVE-2023-53503

MEDIUM EPSS 4.1%
Published Oct 1, 20259mo ago · Modified Jun 17, 20262w ago
5.5 CVSS 3.1
Medium
Find Similar
Published Oct 1, 2025 9mo ago
Last Modified Jun 17, 2026 2w ago

Description

In the Linux kernel, the following vulnerability has been resolved: ext4: allow ext4_get_group_info() to fail Previously, ext4_get_group_info() would treat an invalid group number as BUG(), since in theory it should never happen. However, if a malicious attaker (or fuzzer) modifies the superblock via the block device while it is the file system is mounted, it is possible for s_first_data_block to get set to a very large number. In that case, when calculating the block group of some block number (such as the starting block of a preallocation region), could result in an underflow and very large block group number. Then the BUG_ON check in ext4_get_group_info() would fire, resutling in a denial of service attack that can be triggered by root or someone with write access to the block device. For a quality of implementation perspective, it's best that even if the system administrator does something that they shouldn't, that it will not trigger a BUG. So instead of BUG'ing, ext4_get_group_info() will call ext4_error and return NULL. We also add fallback code in all of the callers of ext4_get_group_info() that it might NULL. Also, since ext4_get_group_info() was already borderline to be an inline function, un-inline it. The results in a next reduction of the compiled text size of ext4 by roughly 2k.

CVSS Details

Base Score
5.5
Exploitability
1.8
Impact
3.6
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
4.1% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-476 NULL Pointer Dereference Memory Safety

Affected Products 5

VendorProductVersionRange
linuxlinux_kernel*≥3.11  –  <5.10.181
linuxlinux_kernel*≥5.11  –  <5.15.113
linuxlinux_kernel*≥5.16  –  <6.1.30
linuxlinux_kernel*≥6.2  –  <6.3.4
linuxlinux_kernel6.4any

References 5

  • git.kernel.org https://git.kernel.org/stable/c/100c0ad6c04597fefeaaba2bb1827cc015d95067
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/31668cebf45adfb6283e465e641c4f5a21b07afa
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/5354b2af34064a4579be8bc0e2f15a7b70f14b5f
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/620a3c28221bb219b81bc0bffd065cc187494302
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/b4319e457d6e3fb33e443efeaf4634fc36e8a9ed
    Patch

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/100c0ad6c04597fefeaaba2bb1827cc015d95067
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/31668cebf45adfb6283e465e641c4f5a21b07afa
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/5354b2af34064a4579be8bc0e2f15a7b70f14b5f
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/620a3c28221bb219b81bc0bffd065cc187494302
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/b4319e457d6e3fb33e443efeaf4634fc36e8a9ed
    Patch