CVE-2026-43284xfrm: esp: avoid in-place decrypt on shared skb frags

Official description

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().

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/a6cb440f274a22456ef3e86b457344f1678f38f9
• https://git.kernel.org/stable/c/ab8b995323e5237041472d07e5055f5f7dcdf15b
• https://git.kernel.org/stable/c/fe785bb3a8096dffcc4048a85cd0c83337eeecad
• https://git.kernel.org/stable/c/5d55c7336f8032d434adcc5fab987ccc93a44aec
• https://git.kernel.org/stable/c/8253aab4659ca16116b522203c2a6b18dccacea7
• https://git.kernel.org/stable/c/50ed1e7873100f77abad20fd31c51029bc49cd03
• https://git.kernel.org/stable/c/b54edf1e9a3fd3491bdcb82a21f8d21315271e0d
• https://git.kernel.org/stable/c/71a1d9d985d26716f74d21f18ee8cac821b06e97
• https://git.kernel.org/stable/c/52646cbd00e765a6db9c3afe9535f26218276034
• https://git.kernel.org/stable/c/f4c50a4034e62ab75f1d5cdd191dd5f9c77fdff4
• http://www.openwall.com/lists/oss-security/2026/05/08/7
• http://www.openwall.com/lists/oss-security/2026/05/13/6
• http://www.openwall.com/lists/oss-security/2026/05/14/2
• http://www.openwall.com/lists/oss-security/2026/05/14/4
• https://www.vicarius.io/vsociety/posts/cve-2026-43284-detection-script-dirty-frag-linux-kernel-local-privilege-escalation
• https://www.vicarius.io/vsociety/posts/cve-2026-43284-mitigation-script-dirty-frag-linux-kernel-local-privilege-escalation
• https://github.com/V4bel/dirtyfrag exploit
• https://access.redhat.com/security/cve/CVE-2026-43284 vdb-entry, x_refsource_REDHAT
• RHBZ#2467771 issue-tracking, x_refsource_REDHAT
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43284.json x_sadp-csaf-vex
• https://access.redhat.com/errata/RHSA-2026:17795 vendor-advisory, x_refsource_REDHAT
• https://access.redhat.com/errata/RHSA-2026:33486 vendor-advisory, x_refsource_REDHAT
• https://access.redhat.com/errata/RHSA-2026:16180 vendor-advisory, x_refsource_REDHAT
• https://access.redhat.com/errata/RHSA-2026:21695 vendor-advisory, x_refsource_REDHAT
• https://access.redhat.com/errata/RHSA-2026:26542 vendor-advisory, x_refsource_REDHAT
• https://access.redhat.com/errata/RHSA-2026:16176 vendor-advisory, x_refsource_REDHAT
• https://access.redhat.com/errata/RHSA-2026:23233 vendor-advisory, x_refsource_REDHAT
• https://access.redhat.com/errata/RHSA-2026:16171 vendor-advisory, x_refsource_REDHAT
• https://access.redhat.com/errata/RHSA-2026:34098 vendor-advisory, x_refsource_REDHAT
• https://access.redhat.com/errata/RHSA-2026:16160 vendor-advisory, x_refsource_REDHAT
• https://access.redhat.com/errata/RHSA-2026:16161 vendor-advisory, x_refsource_REDHAT
• https://access.redhat.com/errata/RHSA-2026:16157 vendor-advisory, x_refsource_REDHAT
• https://access.redhat.com/errata/RHSA-2026:16155 vendor-advisory, x_refsource_REDHAT
• https://access.redhat.com/errata/RHSA-2026:16314 vendor-advisory, x_refsource_REDHAT
• https://access.redhat.com/errata/RHSA-2026:16062 vendor-advisory, x_refsource_REDHAT
• https://access.redhat.com/errata/RHSA-2026:19569 vendor-advisory, x_refsource_REDHAT
• https://access.redhat.com/errata/RHSA-2026:19074 vendor-advisory, x_refsource_REDHAT
• https://access.redhat.com/errata/RHSA-2026:16202 vendor-advisory, x_refsource_REDHAT
• https://access.redhat.com/errata/RHSA-2026:16328 vendor-advisory, x_refsource_REDHAT
• https://access.redhat.com/errata/RHSA-2026:16100 vendor-advisory, x_refsource_REDHAT