CVE-2026-64566

CRITICALCVSS 9.8/10EPSS 0.15%

Last modified

CVE-2026-64566 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. In the Linux kernel, the following vulnerability has been resolved: xfrm: iptfs: propagate SKBFL_SHARED_FRAG in iptfs_skb_add_frags() When iptfs_skb_add_frags() copies frag references from the source frag walk into a new SKB, it increments the page reference count via __skb_frag_ref() but does not propagate SKBFL_SHARED_FRAG to the destination SKB's skb_shinfo->flags. If the source SKB carries shared frags (e.g. from a page-pool backed receive path), the new inner SKB will appear to ESP as having privately owned frags. EPSS estimates a 0.15% chance of exploitation in the next 30 days.

Description

In the Linux kernel, the following vulnerability has been resolved: xfrm: iptfs: propagate SKBFL_SHARED_FRAG in iptfs_skb_add_frags() When iptfs_skb_add_frags() copies frag references from the source frag walk into a new SKB, it increments the page reference count via __skb_frag_ref() but does not propagate SKBFL_SHARED_FRAG to the destination SKB's skb_shinfo->flags. If the source SKB carries shared frags (e.g. from a page-pool backed receive path), the new inner SKB will appear to ESP as having privately owned frags. A subsequent esp_input() call for a nested transport-mode SA then takes the no-COW fast path and decrypts in place, writing over pages that are still referenced by the outer IPTFS SKB. This causes kernel-visible memory corruption and can trigger a panic. All other frag-transfer helpers in the kernel (skb_try_coalesce, skb_gro_receive, __pskb_copy_fclone, skb_shift, skb_segment) correctly propagate SKBFL_SHARED_FRAG; align iptfs_skb_add_frags() with this convention by setting the flag inside the loop immediately after __skb_frag_ref() and nr_frags++, so every exit path that attaches a frag unconditionally propagates SKBFL_SHARED_FRAG.

Metrics

CVSS 3.1
9.8/10

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

EPSS Probability
0.15%

5.1th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= 5f2b6a9095743a6bf1f34c43c4fe78fa8bdf5ad7, < d8aaf06b29f5a0b6186cf68d21c7d63678ee3891; >= 5f2b6a9095743a6bf1f34c43c4fe78fa8bdf5ad7, < ffd64e0717efd83fbf3396ab4e5ac6d795dac4d0; >= 5f2b6a9095743a6bf1f34c43c4fe78fa8bdf5ad7, < 430ea57d6daf765e88f90046afbfd1e071cb7200
LinuxLinux6.14

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-64566?
In the Linux kernel, the following vulnerability has been resolved: xfrm: iptfs: propagate SKBFL_SHARED_FRAG in iptfs_skb_add_frags() When iptfs_skb_add_frags() copies frag references from the source frag walk into a new SKB, it increments the page reference count via __skb_frag_ref() but does not propagate SKBFL_SHARED_FRAG to the destination SKB's skb_shinfo->flags. If the source SKB carries shared frags (e.g. from a page-pool backed receive path), the new inner SKB will appear to ESP as having privately owned frags. A subsequent esp_input() call for a nested transport-mode SA then takes the no-COW fast path and decrypts in place, writing over pages that are still referenced by the outer IPTFS SKB. This causes kernel-visible memory corruption and can trigger a panic. All other frag-transfer helpers in the kernel (skb_try_coalesce, skb_gro_receive, __pskb_copy_fclone, skb_shift, skb_segment) correctly propagate SKBFL_SHARED_FRAG; align iptfs_skb_add_frags() with this convention by setting the flag inside the loop immediately after __skb_frag_ref() and nr_frags++, so every exit path that attaches a frag unconditionally propagates SKBFL_SHARED_FRAG.
How severe is CVE-2026-64566?
CVE-2026-64566 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.15% probability of exploitation in the next 30 days.
How do I fix CVE-2026-64566?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST