How severe is CVE-2025-39931?

CVE-2025-39931 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-2025-39931 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (3rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-39931?

CVE-2025-39931 primarily affects Linux Linux Kernel. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2025-39931?

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

Does CVE-2025-39931 have an EU (EUVD) identifier?

Yes. CVE-2025-39931 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-32399.

When was CVE-2025-39931 published?

CVE-2025-39931 was published on 2025-10-04 and last updated on 2026-07-04.

CVE-2025-39931

CVE-2025-39931 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-908.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
EPSS exploit prediction: 0% (3rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-32399
Weakness: CWE-908
Affected product: Linux Linux Kernel
Published: 2025-10-04
Last modified: 2026-07-04

Description

In the Linux kernel, the following vulnerability has been resolved: crypto: af_alg - Set merge to zero early in af_alg_sendmsg If an error causes af_alg_sendmsg to abort, ctx->merge may contain a garbage value from the previous loop. This may then trigger a crash on the next entry into af_alg_sendmsg when it attempts to do a merge that can't be done. Fix this by setting ctx->merge to zero near the start of the loop.

Frequently asked questions

What is CVE-2025-39931?: In the Linux kernel, the following vulnerability has been resolved: crypto: af_alg - Set merge to zero early in af_alg_sendmsg If an error causes af_alg_sendmsg to abort, ctx->merge may contain a garbage value from the previous loop. This may then trigger a crash on the next entry into af_alg_sendmsg when it attempts to do a merge that can't be done. Fix this by setting ctx->merge to zero near the start of the loop.
How severe is CVE-2025-39931?: CVE-2025-39931 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-2025-39931 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (3rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-39931?: CVE-2025-39931 primarily affects Linux Linux Kernel. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2025-39931?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-39931 have an EU (EUVD) identifier?: Yes. CVE-2025-39931 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-32399.
When was CVE-2025-39931 published?: CVE-2025-39931 was published on 2025-10-04 and last updated on 2026-07-04.

References

Affected products (7)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.17:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.17:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.17:rc5:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.17:rc6:*:*:*:*:*:*

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