CVE-2025-39965 xfrm: xfrm_alloc_spi shouldn't use 0 as SPI

What is CVE-2025-39965?

CVE-2025-39965 is a high-severity use after free vulnerability in Linux kernel, published on 13 Oct 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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

xfrm: xfrm_alloc_spi shouldn't use 0 as SPI

x->id.spi == 0 means "no SPI assigned", but since commit 94f39804d891 ("xfrm: Duplicate SPI Handling"), we now create states and add them to the byspi list with this value.

__xfrm_state_delete doesn't remove those states from the byspi list, since they shouldn't be there, and this shows up as a UAF the next time we go through the byspi list.

Which versions are affected by CVE-2025-39965?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2025-39965?

Apply the vendor's patch.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2025-39965 being exploited?

There is no known exploitation of CVE-2025-39965 in the wild and no public exploit code.

Public exploit code: 1 proofs of concept on GitHub.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-68457, BELL-CVE-2025-39965, DEBIAN-CVE-2025-39965, GHSA-jc8g-4mch-vjcv, ROOT-OS-DEBIAN-13-CVE-2025-39965, UBUNTU-CVE-2025-39965.