VulnerabilityPublished 28 Oct 2026

CVE-2026-99123: Linux kernel · vsock/virtio: validate packet source for connected sockets

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in e9bf92de436ba55f33eaa55d7008e68551123cfd : update Linux kernel when convenient.

Data as of 28 Oct 2026, 10:58 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

Patch: Available – fixed in e9bf92de436ba55f33eaa55d7008e68551123cfd, dee44f41f206becb41c492899c1996cfd7f82a1b, 6cd829de69efd9ed3a53aa2421004a0396eb2bd7

Exploitation evidence

Disclosed: evidence found.
CVE published 28 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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 e9bf92de436ba55f33eaa55d7008e68551123cfd, dee44f41f206becb41c492899c1996cfd7f82a1b or 6cd829de69efd9ed3a53aa2421004a0396eb2bd7.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 06a8fc78367d070720af960dcecec917d3ae5f3b, < e9bf92de436ba55f33eaa55d7008e68551123cfd	Fixed in e9bf92de436ba55f33eaa55d7008e68551123cfd
LinuxLinux	Affected ≥ 06a8fc78367d070720af960dcecec917d3ae5f3b, < dee44f41f206becb41c492899c1996cfd7f82a1b	Fixed in dee44f41f206becb41c492899c1996cfd7f82a1b
LinuxLinux	Affected ≥ 06a8fc78367d070720af960dcecec917d3ae5f3b, < 6cd829de69efd9ed3a53aa2421004a0396eb2bd7	Fixed in 6cd829de69efd9ed3a53aa2421004a0396eb2bd7
LinuxLinux	Affected =4.8	Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: vsock/virtio: validate packet source for connected sockets virtio_transport_recv_pkt() looks up sockets first by the full source and destination tuple, then by destination only in the bound table. The fallback is needed for listening and connecting sockets, but sockets remain in the bound table after connect(), so it can also return a non-listening socket. The fallback does not validate the source address. In TCP_SYN_SENT, a RESPONSE from an unrelated source can transition the victim socket to TCP_ESTABLISHED while its stored remote address remains unchanged. Subsequent RW packets from that source are delivered through the same destination-only fallback. This was reproduced with capability-empty processes under different UIDs. The attacker discovered the target tuple through unprivileged AF_VSOCK sock_diag and caused the victim socket to read 16 attacker-chosen bytes; the intended peer-side socket read 0 of those 16 bytes. Add vsock_check_source() to validate the transport, source port and source CID against the peer stored in a non-listening socket. The local transport is the CID exception because its packets are generated internally with VMADDR_CID_LOCAL as their source, including connections using CID aliases. Use the helper after lock_sock() in the virtio receive path.

References

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