# CVE-2026-99284: net: skbuff: propagate shared-frag marker in skb_zerocopy()

Status: published. Published: 2026-11-07. Updated: 2026-11-07.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Linux / Linux: ≥ af2806f8f90a150160be898cd85332459c83c5cb; < 1c623e3cbf43f12dd4a72712079bfa247a9b8ba3 (affected, git); ≥ af2806f8f90a150160be898cd85332459c83c5cb; < d7d6ff98d5d1b400f02211f962ac32cc0020aeab (affected, git); ≥ af2806f8f90a150160be898cd85332459c83c5cb; < 1a9c180cd8435917b7516edfb1c9148032c28773 (affected, git); ≥ af2806f8f90a150160be898cd85332459c83c5cb; < 79dc34beb1fdb3da79753e51e15c68591a2561fe (affected, git). Source: 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). Source: CNA: Linux

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/1c623e3cbf43f12dd4a72712079bfa247a9b8ba3 (CNA: Linux)

- https://git.kernel.org/stable/c/d7d6ff98d5d1b400f02211f962ac32cc0020aeab (CNA: Linux)

- https://git.kernel.org/stable/c/1a9c180cd8435917b7516edfb1c9148032c28773 (CNA: Linux)

- https://git.kernel.org/stable/c/79dc34beb1fdb3da79753e51e15c68591a2561fe (CNA: Linux)

- https://git.kernel.org/stable/c/1a9c180cd8435917b7516edfb1c9148032c28773 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/1c623e3cbf43f12dd4a72712079bfa247a9b8ba3 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/79dc34beb1fdb3da79753e51e15c68591a2561fe (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/d7d6ff98d5d1b400f02211f962ac32cc0020aeab (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-99284; retrieved 2026-11-07; source updated 2026-11-07

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-99284; retrieved 2026-11-08; source updated 2026-11-07

Revision: f485d4b75d628cad14220d783892f1db475dd9aaad80125254b5e14775a568a0

Canonical: https://y2.dev/cve/CVE-2026-99284

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