CVE-2026-23086: Linux kernel · vsock/virtio: cap TX credit to local buffer size
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 6.8.0-1057.60~22.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 10:12 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 6.8.0-1057.60~22.04.1, 6.8.0-1059.65~22.04.1, 6.8.0-1060.63~22.04.1 +27
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 4 Feb 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.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linuxpkg:deb/ubuntu/linux@6.17.0-40.40?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws@6.17.0-1019.19?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure@6.17.0-1020.20?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.17.0-1017.17?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp@6.17.0-1020.22?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle@6.17.0-1018.18?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
An official fix is available and should be applied to affected Linux kernel versions. The patch caps the transmit buffer size to prevent excessive memory allocation. Systems running affected versions should update to patched kernel releases to mitigate this vulnerability. If QEMU memory is limited with cgroups, memory usage is also constrained, providing additional mitigation. No further action is required once the patch is applied.
Description
A vulnerability in the Linux kernel's vsock/virtio transport allowed a malicious guest to cause excessive memory allocation on the host by advertising a large buffer size and reading data slowly. This could lead to significant memory exhaustion on the host system, potentially causing system instability or requiring process termination to recover. The issue was fixed by bounding the transmit buffer size to the minimum of the peer's advertised buffer and the local buffer allocation, preventing a remote peer from forcing excessive queuing. The fix significantly reduces memory usage under attack conditions, maintaining host stability and guest responsiveness.
References
- ubuntu.com/security/CVE-2026-23086 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-23086 (opens in a new tab)
- git.kernel.org/linus/8ee784fdf006cbe8739cfa093f54d326cbf54037 (opens in a new tab)
- git.kernel.org/stable/c/84ef86aa7120449828d1e0ce438c499014839711 (opens in a new tab)
- git.kernel.org/stable/c/8ee784fdf006cbe8739cfa093f54d326cbf54037 (opens in a new tab)
- git.kernel.org/stable/c/c0e42fb0e054c2b2ec4ee80f48ccd256ae0227ce (opens in a new tab)
- git.kernel.org/stable/c/d9d5f222558b42f6277eafaaa6080966faf37676 (opens in a new tab)
- ubuntu.com/security/notices/USN-8278-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8289-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8296-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8296-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8289-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8278-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8393-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8440-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8499-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8570-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8594-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8604-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8605-1 (opens in a new tab)