CVE-2026-31471: xfrm: iptfs: only publish mode_data after clone setup

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-22 · updated 2026-06-17
Weakness: CWE-415

Description

In the Linux kernel, the following vulnerability has been resolved: xfrm: iptfs: only publish mode_data after clone setup iptfs_clone_state() stores x->mode_data before allocating the reorder window. If that allocation fails, the code frees the cloned state and returns -ENOMEM, leaving x->mode_data pointing at freed memory. The xfrm clone unwind later runs destroy_state() through x->mode_data, so the failed clone path tears down IPTFS state that clone_state() already freed. Keep the cloned IPTFS state private until all allocations succeed so failed clones leave x->mode_data unset. The destroy path already handles a NULL mode_data pointer.

Affected products

Linux kernel: from 6.14 before 6.18.21; from 6.19 before 6.19.11; 7.0-rc1, 7.0-rc2, 7.0-rc3, 7.0-rc4, 7.0-rc5 — fixed in 6.18.21, 6.19.11

How to fix

Upgrade to a fixed version: Linux kernel 6.18.21, 6.19.11. Check the vendor advisory for mitigations.

References

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