VulnerabilityPublished 7 Nov 2026

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

Affects Linux kernelSource CVE Database V5

Compare

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

Data as of 7 Nov 2026, 20:49 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.

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 is available and has been applied in the Linux kernel commits identified by hashes d7d6ff98d5d1b400f02211f962ac32cc0020aeab, 79dc34beb1fdb3da79753e51e15c68591a2561fe, 1c623e3cbf43f12dd4a72712079bfa247a9b8ba3, and 1a9c180cd8435917b7516edfb1c9148032c28773. Users and administrators should update affected Linux kernel versions to these fixed releases or later to remediate the vulnerability.

Description

A vulnerability in the Linux kernel's skb_zerocopy() function causes improper propagation of the shared-frag marker, leading to incorrect handling of shared page-cache backed fragments. This flaw can allow an unprivileged user to write into the page cache of a root-owned read-only file by bypassing expected memory protections during ESP packet processing.

Impact

The vulnerability allows an unprivileged user to write into the page cache of a root-owned read-only file by exploiting the loss of the shared-frag marker during skb_zerocopy() operations. This can lead to unauthorized modification of memory regions that should be protected, potentially compromising system integrity.

Summary

The Linux kernel's skb_zerocopy() function moves fragment descriptors from one socket buffer (skb) to another and takes references on each fragment. However, it fails to copy the skb_shinfo(from)->flags, specifically the SKBFL_SHARED_FRAG marker, into skb_shinfo(to)->flags. This omission causes the destination skb to incorrectly report that it does not have shared fragments. The ESP input processing relies on this marker to decide whether to perform copy-on-write for nonlinear skbs. Without the marker, 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 a root-owned read-only file. The vulnerability is fixed by propagating the SKBFL_SHARED_FRAG flag when frag descriptors are copied.

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 7 Nov 2026, 20:49 UTC

Technical details

References

Community reviews

Related threats