VulnerabilityPublished 28 Oct 2026

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

Source GCVE Database

Authoritative record:CVE-2026-99123

Not known to be exploited · fixed in e9bf92de436ba55f33eaa55d7008e68551123cfd : patch Linux kernel soon.

Data as of 28 Oct 2026, 14:02 UTC

Severity

High

Rated High by Threat Radar's AI analysis · 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.

ghsa-vf8c-hhh3-5w4x

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–

AI-suggested

A fix has been implemented that adds source validation in the vsock/virtio transport receive path. Users should apply the updated Linux kernel version containing this patch. No additional mitigation steps are indicated beyond applying the official fix.

Description

A vulnerability in the Linux kernel's vsock/virtio transport allows an attacker to cause a connected socket to accept packets from an unintended source. This occurs because the fallback socket lookup does not validate the source address, enabling a response from an unrelated source to transition the socket state improperly. The issue was demonstrated with unprivileged processes and could lead to the victim socket reading attacker-chosen data.

Impact

An attacker can cause a victim socket to accept and read data from an unintended source, potentially leading to unauthorized data injection or manipulation at the socket layer. The vulnerability affects the integrity of socket communication in the vsock/virtio transport, allowing attacker-chosen bytes to be read by the victim socket, while the intended peer socket reads none of those bytes.

Summary

The vulnerability in the Linux kernel's vsock/virtio transport arises from the fallback mechanism in virtio_transport_recv_pkt(), which looks up sockets by destination only in the bound table without validating the source address. This can cause a socket in TCP_SYN_SENT state to transition to TCP_ESTABLISHED upon receiving a response from an unrelated source, while the stored remote address remains unchanged. Subsequent packets from that source are accepted and delivered. The flaw was reproducible by unprivileged processes using AF_VSOCK sock_diag to discover target tuples and inject data. The fix involves adding vsock_check_source() to validate transport, source port, and source CID against the peer stored in non-listening sockets, applied after lock_sock() in the receive path.

References

Community reviews

Loading reviews…