5.5

CVE-2023-53503: ext4: allow ext4_get_group_info() to fail

Analyzed
AliasesUBUNTU-CVE-2023-53503DEBIAN-CVE-2023-53503
Published 01-10-2025Last modified 11-05-2026

Vulnerability summary

CVE-2023-53503 is a medium (CVSS 5.5) NULL Pointer Dereference vulnerability in linux. EPSS estimates a 0.16% chance of exploitation in the next 30 days, higher than 5% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
5.5/10
010
Medium · v3.1 (NVD)
EPSS score
0.16%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 2
RHSA-2024:10771RHSA-2024:9315

Timeline

  1. 01-10-2025
    PublishedVulnerability first disclosed.
  2. 11-05-2026
    Last modifiedVulnerability 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

4 scores · 3 sources · 2 versions

EPSS trend

Probability

0.16%

Chance of exploitation in the next 30 days

Percentile

5%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.15% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu124 products
  • linuxAll versions (No fix recorded) | < 5.15.0-83.92
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-awsAll versions (No fix recorded) | < 5.15.0-1044.49
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ 2f2e09eb15849562aede80ed007658e4504ded26, < 100c0ad6c04597fefeaaba2bb1827cc015d95067 | ≥ 2f2e09eb15849562aede80ed007658e4504ded26, < 620a3c28221bb219b81bc0bffd065cc187494302 | ≥ 2f2e09eb15849562aede80ed007658e4504ded26, < b4319e457d6e3fb33e443efeaf4634fc36e8a9ed | ≥ 2f2e09eb15849562aede80ed007658e4504ded26, < 31668cebf45adfb6283e465e641c4f5a21b07afa | ≥ 2f2e09eb15849562aede80ed007658e4504ded26, < 5354b2af34064a4579be8bc0e2f15a7b70f14b5f | 3.11
  • 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
Debian1 product
  • linux< 6.1.37-1 | < 6.3.7-1

3 vendors · 127 products

References

9 links