CVE-2026-43284highobserved exploitationCWE-123

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

100Vexday Risk Score

Patch now. It exploitation observed by VulnCheck and has a working public exploit.

ssvc Actcvss 8.8epss 93%

from disclosure to weapon0 days

Published on NVDMay 8

1st PoCMay 5

metasploitMay 8

VulnCheckMay 8

exploitation probability

93%top 1% of all CVEs

observed exploitation

yesVulnCheck

53 public exploit(s)

What the vendors declare (VEX)

Official vendor statements in CSAF/VEX format: whether their product is affected, already fixed, or ruled out — and why. These are the vendor's assertions, not Vexday's judgment.

Red HatVEX document ↗

Affected

1 product

Red Hat OpenShift Container Platform 4

workaround: See the security bulletin for a detailed mitigation procedure.

Fixed

55 products (3,875 components)

Red Hat Enterprise Linux BaseOS (v. 10) · Red Hat Enterprise Linux BaseOS (v. 9) · Red Hat Enterprise Linux AppStream (v. 10) · Red Hat Enterprise Linux AppStream (v. 9) · Red Hat Enterprise Linux Real Time (v. 10) · and others 50

fix ↗

Not affected

2 products (42 components) — because the vulnerable code is not present in the product

Red Hat Enterprise Linux 7 · Red Hat Enterprise Linux 6

In short

A vulnerability in Linux kernel ESP (Encapsulating Security Payload) encryption allows attackers to decrypt data in-place on shared memory pages when using UDP with MSG_SPLICE_PAGES, potentially exposing sensitive packet contents.

Technical detail

The ESP input path in the Linux kernel fails to mark shared skb fragments with SKBFL_SHARED_FRAG when UDP datagrams splice pages from pipes, allowing in-place decryption over externally-backed memory. The no-COW fast path assumes exclusive ownership of uncloned nonlinear skbs, but shared pipe pages violate this assumption. Fix requires setting the shared fragment flag for UDP splice operations and falling back to skb_cow_data() in ESP input when the flag is present.

Summary generated and translated by AI from the 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().

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

Affected products

Linux · Linux

public PoCs found — 53

⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.

References