CVE-2026-43284

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().

From the Tenable Blog

Dirty Frag (CVE-2026-43284,CVE-2026-43500): Linux Kernel Privilege Escalation FAQ | Tenable®

Published: 2026-05-08

Dirty Frag (CVE-2026-43284, CVE-2026-43500) is a Linux kernel local privilege escalation exploit chain with a public PoC affecting major Linux distributions.

References

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Details

Source: Mitre, NVD

Named Vulnerability: copy.fail 2Named Vulnerability: DirtyFragNamed Vulnerability: Dirty FragNamed Vulnerability: Copy Fail 2

Risk Information

CVSS v2

CVSS v3

EPSS

Vulnerability Watch

Tenable Research has classified this CVE under the following Vulnerability Watch classification, which includes active and historical (inactive) classifications. You can learn more about these classifications on our blog.

Vulnerability of Interest