CVE-2026-23069 vsock/virtio: fix potential underflow in virtio_transport_get_credit()
An integer underflow in the Linux kernel's vsock/virtio transport allows excessive data queuing, potentially leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-23069?
CVE-2026-23069 is a medium-severity vulnerability in Linux kernel, published on 4 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
vsock/virtio: fix potential underflow in virtio_transport_get_credit()
The credit calculation in virtio_transport_get_credit() uses unsigned arithmetic:
ret = vvs->peer_buf_alloc - (vvs->tx_cnt - vvs->peer_fwd_cnt);
If the peer shrinks its advertised buffer (peer_buf_alloc) while bytes are in flight, the subtraction can underflow and produce a large positive value, potentially allowing more data to be queued than the peer can handle.
Reuse virtio_transport_has_space() which already handles this case and add a comment to make it clear why we are doing that.
[Stefano: use virtio_transport_has_space() instead of duplicating the code] [Stefano: tweak the commit message]
Which versions are affected by CVE-2026-23069?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-23069?
Apply the vendor's patch.
Is CVE-2026-23069 being exploited?
There is no known exploitation of CVE-2026-23069 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-77130, BELL-CVE-2026-23069, DEBIAN-CVE-2026-23069, GHSA-pwx7-84p4-42qc, ROOT-OS-DEBIAN-11-CVE-2026-23069, ROOT-OS-DEBIAN-12-CVE-2026-23069 and 4 more.