CVE-2026-99284
net: skbuff: propagate shared-frag marker in skb_zerocopy()
In the Linux kernel, the following vulnerability has been resolved: net: skbuff: propagate shared-frag marker in skb_zerocopy() skb_zerocopy() moves frag descriptors from @from into @to and takes a reference on each frag, but it does not copy skb_shinfo(from)->flags into skb_shinfo(to)->flags. A destination skb holding the same page-cache backed frags as the source therefore reports skb_has_shared_frag() as false. That breaks the invariant relied on by later in-place writers. ESP input checks skb_has_shared_frag() before deciding whether an uncloned nonlinear skb can skip skb_cow_data(); with the marker lost, an skb that skb_zerocopy() built for nfnetlink_queue or for an openvswitch upcall is decrypted in place, letting an unprivileged user write into the page cache of a root-owned read-only file. Propagate SKBFL_SHARED_FRAG when frag descriptors are copied, as done for the other frag-transfer helpers.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| Linux Linux |
≥ af2806f8f90a150160be898cd85332459c83c5cb; < 1c623e3cbf43f12dd4a72712079bfa247a9b8ba3 (affected, git) ≥ af2806f8f90a150160be898cd85332459c83c5cb; < d7d6ff98d5d1b400f02211f962ac32cc0020aeab (affected, git) ≥ af2806f8f90a150160be898cd85332459c83c5cb; < 1a9c180cd8435917b7516edfb1c9148032c28773 (affected, git) ≥ af2806f8f90a150160be898cd85332459c83c5cb; < 79dc34beb1fdb3da79753e51e15c68591a2561fe (affected, git) Other versions: unaffected |
CNA: Linux |
| Linux Linux |
3.14 (affected) ≥ 0; < 3.14 (unaffected, semver) ≥ 6.18.61; ≤ 6.18.* (unaffected, semver) ≥ 7.2.15; ≤ 7.2.* (unaffected, semver) ≥ 7.3.2; ≤ 7.3.* (unaffected, semver) ≥ 7.4-rc1; ≤ * (unaffected, original_commit_for_fix) Other versions: affected |
CNA: Linux |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
No CVSS assessment reported. An unscored record is not a low-severity determination.
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://git.kernel.org/stable/c/1c623e3cbf43f12dd4a72712079bfa247a9b8ba3CNA: Linux
- https://git.kernel.org/stable/c/d7d6ff98d5d1b400f02211f962ac32cc0020aeabCNA: Linux
- https://git.kernel.org/stable/c/1a9c180cd8435917b7516edfb1c9148032c28773CNA: Linux
- https://git.kernel.org/stable/c/79dc34beb1fdb3da79753e51e15c68591a2561feCNA: Linux
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