CVE-2026-46300

Description

In the Linux kernel, the following vulnerability has been resolved: net: skbuff: preserve shared-frag marker during coalescing skb_try_coalesce() can attach paged frags from @from to @to. If @from has SKBFL_SHARED_FRAG set, the resulting @to skb can contain the same externally-owned or page-cache-backed frags, but the shared-frag marker is currently lost. That breaks the invariant relied on by later in-place writers. In particular, ESP input checks skb_has_shared_frag() before deciding whether an uncloned nonlinear skb can skip skb_cow_data(). If TCP receive coalescing has moved shared frags into an unmarked skb, ESP can see skb_has_shared_frag() as false and decrypt in place over page-cache backed frags. Propagate SKBFL_SHARED_FRAG when skb_try_coalesce() transfers paged frags. The tailroom copy path does not need the marker because it copies bytes into @to's linear data rather than transferring frag descriptors.

From the Tenable Blog

CVE-2026-46300 (Fragnesia): Linux Kernel ESP-in-TCP LPE FAQ | Tenable®

Published: 2026-05-14

CVE-2026-46300 (Fragnesia) is a Linux kernel privilege escalation in the XFRM ESP-in-TCP subsystem. Public PoC, no race condition. Dirty Frag patches do not fix it.

References

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Details

Source: Mitre, NVD

Named Vulnerability: Fragnesia

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