CVE-2023-53503

Advisory lineage Upstream: 0 Downstream: 4
Analyzed
Published: 01 Oct 2025, 11:45
Last modified:11 May 2026, 19:46

Vulnerability Summary

Overall Risk (default)
low
22/100
CVSS Score
5.5 MEDIUM
v3.1 (nvd)
EPSS Score
0.03% LOW
0% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

01 Oct 2025, 11:45
Published
Vulnerability first disclosed
11 May 2026, 19:46
Last Modified
Vulnerability information updated

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 Metrics

  • v3.1•MEDIUM•Score: 5.5CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Trends

Current EPSS score: 0.03%• Percentile: 9%

Techniques & Countermeasures

  • CWE-476•NULL Pointer Dereference

    The product dereferences a pointer that it expects to be valid but is NULL.

Affected Systems

  • linux•linux

    ≥ 2f2e09eb15849562aede80ed007658e4504ded26, < 100c0ad6c04597fefeaaba2bb1827cc015d95067 | ≥ 2f2e09eb15849562aede80ed007658e4504ded26, < 620a3c28221bb219b81bc0bffd065cc187494302 | ≥ 2f2e09eb15849562aede80ed007658e4504ded26, < b4319e457d6e3fb33e443efeaf4634fc36e8a9ed | ≥ 2f2e09eb15849562aede80ed007658e4504ded26, < 31668cebf45adfb6283e465e641c4f5a21b07afa | ≥ 2f2e09eb15849562aede80ed007658e4504ded26, < 5354b2af34064a4579be8bc0e2f15a7b70f14b5f | 3.11

  • linux•linux_kernel

    ≥ 3.11, < 5.10.181 | ≥ 5.11, < 5.15.113 | ≥ 5.16, < 6.1.30 | ≥ 6.2, < 6.3.4 | 6.4:rc1

References (5)