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CVE-2026-43284

High · CVSS 8.8

Linux Kernel — In-place decryption on shared skb frags (write-what-where / buffer misuse via shared pipe pages)

CVSS
8.8
nvd
EPSS
93.2%
100th pct
KEV
No
Class
oss containerizable
CWE-123, CWE-123

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().

Search profile — drives PoC discovery

Symbols SKBFL_SHARED_FRAGskb_splice_from_iterskb_cow_dataesp_output_headMSG_SPLICE_PAGESskb_tailroomfrag_listesp_inputxfrm_espskb->data_len
Keywords CVE-2026-43284xfrm esp shared skb fragsSKBFL_SHARED_FRAG ESP decryptESP-in-UDP shared pipe pagesLinux kernel xfrm esp COW decryptskb_cow_data esp input shared fragMSG_SPLICE_PAGES UDP skb ESPxfrm esp in-place decrypt PoCLinux kernel ESP shared frag exploit
Versions: Fixed in commits: 50ed1e7873100f77abad20fd31c51029bc49cd03, 52646cbd00e765a6db9c3afe9535f26218276034, 5d55c7336f8032d434adcc5fab987ccc93a44aec, 71a1d9d985d26716f74d21f18ee8cac821b06e97, 8253aab4659ca16116b522203c2a6b18dccacea7

Ranked PoCs (33) — best first

Heuristic ranking — not yet expert-vetted. Scored on structure + provenance, not execution.

Recall-favoring discovery; ranking by the Stage-4 scorer (Adam's rubric). Scanner/aggregator repos are hidden.

Affected packages

Linux Kernel 0 → 6.1.171
Linux Kernel 0 → 6.6.138
Linux Kernel 4.11.0 → 5.10.255
Linux Kernel 5.11.0 → 5.15.205
Linux Kernel 5.16.0 → 5.15.206
Linux Kernel 6.13.0 → 6.18.28
Linux Kernel 6.19.0 → 7.0.5
Linux Kernel 6.2.0 → 6.1.172
Linux Kernel 6.7.0 → 6.12.87

References

Status: enriched · ingested 2026-07-10T18:00:26.000Z · profiled 2026-07-10T18:30:26.000Z