CVE-2026-63970: Linux kernel · vsock/virtio: bind uarg before filling zerocopy skb
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 7.8 High · fixed in b62e2b2b4a50953ca952f3cd3f77dd62dc50fd5d : patch Linux kernel soon.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Total control over the software or total information disclosure
CISA SSVC assessment, 2026-10-16.
- Patch
- Available – fixed in b62e2b2b4a50953ca952f3cd3f77dd62dc50fd5d, 72194f65050958e4c8e069adb6c5d89ef81ca197, 5d317573f1d48e76cce5fb6250452b6e4102e0fb +1
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 19 Jul 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 Linux kernel to b62e2b2b4a50953ca952f3cd3f77dd62dc50fd5d, 72194f65050958e4c8e069adb6c5d89ef81ca197, 5d317573f1d48e76cce5fb6250452b6e4102e0fb or 1e584c304cfb94a759417130b1fc6d30b30c4cce.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in– |
Description
In the Linux kernel, the following vulnerability has been resolved: vsock/virtio: bind uarg before filling zerocopy skb virtio_transport_send_pkt_info() allocates or reuses the zerocopy uarg before entering the send loop, but virtio_transport_alloc_skb() still fills the skb before it inherits that uarg. When fixed-buffer vectored zerocopy hits MAX_SKB_FRAGS, io_sg_from_iter() may partially attach managed frags and return -EMSGSIZE. The rollback path call kfree_skb() to free an skb that carries SKBFL_MANAGED_FRAG_REFS but no uarg, so skb_release_data() falls through to ordinary frag unref. Pass the uarg into virtio_transport_alloc_skb() and bind it immediately before virtio_transport_fill_skb(). This keeps control or no-payload skbs untouched while ensuring success and rollback share one lifetime rule.
References
- git.kernel.org/stable/c/72194f65050958e4c8e069adb6c5d89ef81ca197 (opens in a new tab)
- git.kernel.org/stable/c/b62e2b2b4a50953ca952f3cd3f77dd62dc50fd5d (opens in a new tab)
- git.kernel.org/stable/c/5d317573f1d48e76cce5fb6250452b6e4102e0fb (opens in a new tab)
- git.kernel.org/stable/c/1e584c304cfb94a759417130b1fc6d30b30c4cce (opens in a new tab)