How severe is CVE-2023-34256?

CVE-2023-34256 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2023-34256 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (16th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-34256?

CVE-2023-34256 primarily affects Linux Linux Kernel. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-34256?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2023-34256 published?

CVE-2023-34256 was published on 2023-05-31 and last updated on 2026-06-17.

CVE-2023-34256

CVE-2023-34256 is a medium-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-125.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
EPSS exploit prediction: 0% (16th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-125
Affected product: Linux Linux Kernel
Published: 2023-05-31
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2023-34256?: 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.
How severe is CVE-2023-34256?: CVE-2023-34256 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2023-34256 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (16th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-34256?: CVE-2023-34256 primarily affects Linux Linux Kernel. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-34256?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2023-34256 published?: CVE-2023-34256 was published on 2023-05-31 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:suse:linux_enterprise:12.0:sp5:*:*:*:*:*:*
cpe:2.3:o:suse:linux_enterprise:15.0:sp4:*:*:*:*:*:*
cpe:2.3:o:suse:linux_enterprise:15.0:sp5:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

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