CVE-2026-74684: Linux kernel · net: tap: set skb->dev before parsing virtio net header in tap_get_user_xdp()
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 7.1 High · fixed in 3874892dd27d5387aa9a06f58d9060f18f351d24 : patch Linux kernel soon.
Data as of 26 Oct 2026, 15:59 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 3% 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
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-10-16.
- Patch
- Available – fixed in 3874892dd27d5387aa9a06f58d9060f18f351d24, 15583b07fd691a844fbf7b3ad612cdc9e9a657c0, 164c31ee252ebd1ac8f44c2dfc5486b6d9a0379b +7
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 22 Aug 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 |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in– |
Description
In the Linux kernel, the following vulnerability has been resolved: net: tap: set skb->dev before parsing virtio net header in tap_get_user_xdp() The commit 4f61f133f354 ("net: tap: NULL pointer derefence in dev_parse_header_protocol when skb->dev is null") fixed a crash in tap_get_user() by assigning skb->dev before calling tun_vnet_hdr_to_skb(). This is required because virtio_net_hdr_to_skb() may invoke dev_parse_header_protocol(), which dereferences skb->dev. Without the assignment, a NULL pointer dereference can occur. However, tap_get_user_xdp() still parses the virtio-net header before assigning skb->dev. When the vhost TX path passes an XDP buffer containing a GSO virtio-net header but the protocol is set to zero on purpose, tun_vnet_hdr_to_skb() can reach dev_parse_header_protocol() while skb->dev is still NULL, resulting in a crash. Fix this by looking up the tap device and assigning skb->dev before calling tun_vnet_hdr_to_skb(), matching the ordering already used in tap_get_user(). Preserve the existing RCU read-side critical section across dev_queue_xmit().
References
- git.kernel.org/stable/c/61dd022c55c7307ec119e5672cb141cccbecf3b1 (opens in a new tab)
- git.kernel.org/stable/c/15583b07fd691a844fbf7b3ad612cdc9e9a657c0 (opens in a new tab)
- git.kernel.org/stable/c/8b444b126cd8e4473e652f529753ed4dd1360a9c (opens in a new tab)
- git.kernel.org/stable/c/164c31ee252ebd1ac8f44c2dfc5486b6d9a0379b (opens in a new tab)
- git.kernel.org/stable/c/3874892dd27d5387aa9a06f58d9060f18f351d24 (opens in a new tab)