VulnerabilityPublished 7 Nov 2026

CVE-2026-99284: Linux kernel · net: skbuff: propagate shared-frag marker in skb_zerocopy()

Source GCVE Database

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Authoritative record:CVE-2026-99284· High

Not known to be exploited · fixed in d7d6ff98d5d1b400f02211f962ac32cc0020aeab : patch Linux kernel soon.

Data as of 7 Nov 2026, 22:49 UTC

Severity

High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

Thin evidence

One scorer or none

Patch: Available – fixed in d7d6ff98d5d1b400f02211f962ac32cc0020aeab, 79dc34beb1fdb3da79753e51e15c68591a2561fe, 1c623e3cbf43f12dd4a72712079bfa247a9b8ba3 +1

Exploitation evidence

Disclosed: evidence found.
CVE published 7 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 7 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-j3jv-p835-c5gh

What to do

Upgrade Linux kernel to d7d6ff98d5d1b400f02211f962ac32cc0020aeab, 79dc34beb1fdb3da79753e51e15c68591a2561fe, 1c623e3cbf43f12dd4a72712079bfa247a9b8ba3 or 1a9c180cd8435917b7516edfb1c9148032c28773.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ af2806f8f90a150160be898cd85332459c83c5cb, < d7d6ff98d5d1b400f02211f962ac32cc0020aeab	Fixed in d7d6ff98d5d1b400f02211f962ac32cc0020aeab
LinuxLinux	Affected ≥ af2806f8f90a150160be898cd85332459c83c5cb, < 79dc34beb1fdb3da79753e51e15c68591a2561fe	Fixed in 79dc34beb1fdb3da79753e51e15c68591a2561fe
LinuxLinux	Affected ≥ af2806f8f90a150160be898cd85332459c83c5cb, < 1c623e3cbf43f12dd4a72712079bfa247a9b8ba3	Fixed in 1c623e3cbf43f12dd4a72712079bfa247a9b8ba3
LinuxLinux	Affected ≥ af2806f8f90a150160be898cd85332459c83c5cb, < 1a9c180cd8435917b7516edfb1c9148032c28773	Fixed in 1a9c180cd8435917b7516edfb1c9148032c28773
LinuxLinux	Affected =3.14	Fixed in–

AI-suggested

A fix has been implemented to propagate the SKBFL_SHARED_FRAG flag correctly during frag descriptor copying in skb_zerocopy(). Users should apply the official Linux kernel patch that addresses this issue. Since this is a kernel vulnerability, updating to a fixed kernel version is the recommended remediation. No alternative mitigations are indicated.

Description

A vulnerability in the Linux kernel's skb_zerocopy() function causes improper propagation of the shared-frag marker. This leads to incorrect assumptions about shared fragments in socket buffers, allowing certain in-place decryption operations to overwrite page cache memory. An unprivileged user can exploit this to write into the page cache of root-owned read-only files.

Impact

This vulnerability allows an unprivileged user to write into the page cache of root-owned read-only files by bypassing checks that prevent in-place modification of shared fragments. This could lead to unauthorized modification of critical system files or data, potentially compromising system integrity and security.

Summary

The Linux kernel's skb_zerocopy() function moves frag descriptors between socket buffers and takes references on each frag but fails to copy the skb_shinfo flags, specifically the SKBFL_SHARED_FRAG marker. This omission causes skb_has_shared_frag() to return false incorrectly, breaking invariants relied upon by later in-place writers such as the ESP input processing. Consequently, an skb constructed by skb_zerocopy() for nfnetlink_queue or openvswitch upcalls can be decrypted in place, enabling an unprivileged user to write into the page cache of root-owned read-only files. The fix involves propagating the SKBFL_SHARED_FRAG flag when frag descriptors are copied, aligning with other frag-transfer helpers.

References

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