CVE-2026-46300 — net: skbuff: preserve shared-frag marker during coalescing

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
Linux / Linux	affected cef401de7be8c4e155c6746bfccf721a4fa5fab9 before 3599e6b3cc1ada96883d496a50a210d3afbb6987; affected cef401de7be8c4e155c6746bfccf721a4fa5fab9 before 2f2b16022a2e10ca7bccfb98db5ed2ec0f72641c; affected cef401de7be8c4e155c6746bfccf721a4fa5fab9 before 9d3e5fd19fe1063bf607219e8562fbd567b8e8d5; affected cef401de7be8c4e155c6746bfccf721a4fa5fab9 before 78bf6b6bb19541d19fbda6242e7cfe2c682763c0; affected cef401de7be8c4e155c6746bfccf721a4fa5fab9 before 760e1addc27ba1a7beb4a0a7e8b3e9ec49e7a34e; affected cef401de7be8c4e155c6746bfccf721a4fa5fab9 before 3bd9e113d50034db99d7ef69fd8e5242d15e414a; affected cef401de7be8c4e155c6746bfccf721a4fa5fab9 before 3884358a9286b17f389a72b1426fc4547c23c111; affected cef401de7be8c4e155c6746bfccf721a4fa5fab9 before f84eca5817390257cef78013d0112481c503b4a3
Linux / Linux	affected 3.9; unaffected 0 before 3.9; unaffected 5.10.257 through 5.10.; unaffected 5.15.208 through 5.15.; unaffected 6.1.174 through 6.1.; unaffected 6.6.141 through 6.6.; unaffected 6.12.91 through 6.12.; unaffected 6.18.33 through 6.18.; unaffected 7.0.10 through 7.0.; unaffected 7.1 through

Vendor / product

Versions

Linux / Linux

affected cef401de7be8c4e155c6746bfccf721a4fa5fab9 before 3599e6b3cc1ada96883d496a50a210d3afbb6987; affected cef401de7be8c4e155c6746bfccf721a4fa5fab9 before 2f2b16022a2e10ca7bccfb98db5ed2ec0f72641c; affected cef401de7be8c4e155c6746bfccf721a4fa5fab9 before 9d3e5fd19fe1063bf607219e8562fbd567b8e8d5; affected cef401de7be8c4e155c6746bfccf721a4fa5fab9 before 78bf6b6bb19541d19fbda6242e7cfe2c682763c0; affected cef401de7be8c4e155c6746bfccf721a4fa5fab9 before 760e1addc27ba1a7beb4a0a7e8b3e9ec49e7a34e; affected cef401de7be8c4e155c6746bfccf721a4fa5fab9 before 3bd9e113d50034db99d7ef69fd8e5242d15e414a; affected cef401de7be8c4e155c6746bfccf721a4fa5fab9 before 3884358a9286b17f389a72b1426fc4547c23c111; affected cef401de7be8c4e155c6746bfccf721a4fa5fab9 before f84eca5817390257cef78013d0112481c503b4a3

Linux / Linux

affected 3.9; unaffected 0 before 3.9; unaffected 5.10.257 through 5.10.*; unaffected 5.15.208 through 5.15.*; unaffected 6.1.174 through 6.1.*; unaffected 6.6.141 through 6.6.*; unaffected 6.12.91 through 6.12.*; unaffected 6.18.33 through 6.18.*; unaffected 7.0.10 through 7.0.*; unaffected 7.1 through *

CWE

No CWE identifiers supplied.

References

ADP enrichment

CVE

No English description supplied.

redhat-SADP

A flaw was found in the Linux kernel's XFRM ESP-in-TCP subsystem. Unsafe in-place cryptographic processing allows a low-privileged local attacker to write arbitrary bytes into the page cache of read-only files, including sensitive system files. An attacker can exploit this to overwrite privileged binaries and gain root privileges.

siemens-SADP

No English description supplied.

CISA-ADP

No English description supplied.

No references supplied.