CVE-2023-34256

Name: CVE-2023-34256
Creator: NVD / NIST
Published: 2023-05-31T20:15:10.817+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.5/10EPSS 0.25%

Last modified Jun 17, 2026

CVE-2023-34256 is a medium-severity vulnerability rated 5.5/10 on the CVSS scale. An issue was discovered in the Linux kernel before 6.3.3. There is an out-of-bounds read in crc16 in lib/crc16.c when called from fs/ext4/super.c because ext4_group_desc_csum does not properly check an offset. EPSS estimates a 0.25% chance of exploitation in the next 30 days.

Description

An issue was discovered in the Linux kernel before 6.3.3. There is an out-of-bounds read in crc16 in lib/crc16.c when called from fs/ext4/super.c because ext4_group_desc_csum does not properly check an offset. NOTE: this is disputed by third parties because the kernel is not intended to defend against attackers with the stated "When modifying the block device while it is mounted by the filesystem" access.

Metrics

CVSS 3.1

5.5/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

0.25%

15.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions	Update
Linux	Linux Kernel	< 6.3.3	—
Suse	Linux Enterprise	12.0	Sp5
Suse	Linux Enterprise	15.0	Sp4
Debian	Debian Linux	10.0	—

References

https://bugzilla.suse.com/show_bug.cgi?id=1211895Issue Tracking, Patch, Third Party Advisory
https://cdn.kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.3.3Mailing List, Patch
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4f04351888a83e595571de672e0a4a8b74f4fb31Mailing List, Patch
https://lists.debian.org/debian-lts-announce/2023/07/msg00030.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/10/msg00027.htmlMailing List, Third Party Advisory
https://syzkaller.appspot.com/bug?extid=8785e41224a3afd04321Mailing List, Patch
https://bugzilla.suse.com/show_bug.cgi?id=1211895Issue Tracking, Patch, Third Party Advisory
https://cdn.kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.3.3Mailing List, Patch
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4f04351888a83e595571de672e0a4a8b74f4fb31Mailing List, Patch
https://lists.debian.org/debian-lts-announce/2023/07/msg00030.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/10/msg00027.htmlMailing List, Third Party Advisory
https://syzkaller.appspot.com/bug?extid=8785e41224a3afd04321Mailing List, Patch

Timeline

Published: May 31, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2023-34256?

How severe is CVE-2023-34256?

CVE-2023-34256 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.25% probability of exploitation in the next 30 days.

How do I fix CVE-2023-34256?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2023-34256?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST