What is the CVSS score of CVE-2025-39939?

CVE-2025-39939 has a CVSS 3.1 base score of 7.8 (High). CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

Which versions of Linux Kernel are affected by CVE-2025-39939?

CVE-2025-39939 presents notable security risk, a out-of-bounds write vulnerability rated CVSS 7.8.. A patch is available.

Is there a public PoC exploit available for CVE-2025-39939?

Yes, a public proof-of-concept exploit is available for CVE-2025-39939. Prioritise patching immediately. EPSS: 0.0%.

How to fix or mitigate CVE-2025-39939?

Within 7 days: Identify all affected systems and apply vendor patches promptly. If patching is delayed, consider network segmentation to limit exposure.

Linux Kernel CVE-2025-39939

EUVD-2025-32386 HIGH

Out-of-bounds Write (CWE-787)

2025-10-04 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Buffer Overflow Linux Memory Corruption Red Hat Linux Kernel Suse

7.8

CVSS 3.1

CVSS VectorNVD

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

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

PoC Detected

Mar 25, 2026 - 00:44 vuln.today

Public exploit code

Patch released

Mar 25, 2026 - 00:44 nvd

Patch available

EUVD ID Assigned

Mar 13, 2026 - 19:56 euvd

EUVD-2025-32386

Analysis Generated

Mar 13, 2026 - 19:56 vuln.today

CVE Published

Oct 04, 2025 - 08:15 nvd

HIGH 7.8

DescriptionNVD

In the Linux kernel, the following vulnerability has been resolved:

iommu/s390: Fix memory corruption when using identity domain

zpci_get_iommu_ctrs() returns counter information to be reported as part of device statistics; these counters are stored as part of the s390_domain. The problem, however, is that the identity domain is not backed by an s390_domain and so the conversion via to_s390_domain() yields a bad address that is zero'd initially and read on-demand later via a sysfs read. These counters aren't necessary for the identity domain; just return NULL in this case.

This issue was discovered via KASAN with reports that look like: BUG: KASAN: global-out-of-bounds in zpci_fmb_enable_device when using the identity domain for a device on s390.

AnalysisAI

In the Linux kernel, the following vulnerability has been resolved: iommu/s390: Fix memory corruption when using identity domain zpci_get_iommu_ctrs() returns counter information to be reported as part of device statistics; these counters are...

Technical ContextAI

An out-of-bounds memory access occurs when code reads from or writes to memory locations outside the intended buffer boundaries. This vulnerability is classified as Out-of-bounds Write (CWE-787).

RemediationAI

A vendor patch is available — apply it immediately. Implement proper bounds checking on all array and buffer accesses. Use memory-safe languages or static analysis tools to detect OOB issues.