Linux Kernel ESP: Prevent In-Place Decrypt on Shared skb Frags
CVE-2026-43284 Published on May 8, 2026
xfrm: esp: avoid in-place decrypt on shared skb frags
In the Linux kernel, the following vulnerability has been resolved:
xfrm: esp: avoid in-place decrypt on shared skb frags
MSG_SPLICE_PAGES can attach pages from a pipe directly to an skb. TCP
marks such skbs with SKBFL_SHARED_FRAG after skb_splice_from_iter(),
so later paths that may modify packet data can first make a private
copy. The IPv4/IPv6 datagram append paths did not set this flag when
splicing pages into UDP skbs.
That leaves an ESP-in-UDP packet made from shared pipe pages looking
like an ordinary uncloned nonlinear skb. ESP input then takes the no-COW
fast path for uncloned skbs without a frag_list and decrypts in place
over data that is not owned privately by the skb.
Mark IPv4/IPv6 datagram splice frags with SKBFL_SHARED_FRAG, matching
TCP. Also make ESP input fall back to skb_cow_data() when the flag is
present, so ESP does not decrypt externally backed frags in place.
Private nonlinear skb frags still use the existing fast path.
This intentionally does not change ESP output. In esp_output_head(),
the path that appends the ESP trailer to existing skb tailroom without
calling skb_cow_data() is not reachable for nonlinear skbs:
skb_tailroom() returns zero when skb->data_len is nonzero, while ESP
tailen is positive. Thus ESP output will either use the separate
destination-frag path or fall back to skb_cow_data().
Products Associated with CVE-2026-43284
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Affected Versions
Linux:- Version cac2661c53f35cbe651bef9b07026a5a05ab8ce0 and below a6cb440f274a22456ef3e86b457344f1678f38f9 is affected.
- Version cac2661c53f35cbe651bef9b07026a5a05ab8ce0 and below ab8b995323e5237041472d07e5055f5f7dcdf15b is affected.
- Version cac2661c53f35cbe651bef9b07026a5a05ab8ce0 and below 5d55c7336f8032d434adcc5fab987ccc93a44aec is affected.
- Version cac2661c53f35cbe651bef9b07026a5a05ab8ce0 and below 50ed1e7873100f77abad20fd31c51029bc49cd03 is affected.
- Version cac2661c53f35cbe651bef9b07026a5a05ab8ce0 and below b54edf1e9a3fd3491bdcb82a21f8d21315271e0d is affected.
- Version cac2661c53f35cbe651bef9b07026a5a05ab8ce0 and below 71a1d9d985d26716f74d21f18ee8cac821b06e97 is affected.
- Version cac2661c53f35cbe651bef9b07026a5a05ab8ce0 and below 52646cbd00e765a6db9c3afe9535f26218276034 is affected.
- Version 4.11 is affected.
- Before 4.11 is unaffected.
- Version 5.10.255, <= 5.10.* is unaffected.
- Version 5.15.205, <= 5.15.* is unaffected.
- Version 6.1.171, <= 6.1.* is unaffected.
- Version 6.6.138, <= 6.6.* is unaffected.
- Version 6.12.87, <= 6.12.* is unaffected.
- Version 6.18.28, <= 6.18.* is unaffected.
- Version 7.0.5, <= 7.0.* is unaffected.