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CVE-2026-74684

Unknown

Last modified

CVE-2026-74684 is a vulnerability of currently unknown severity. 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.

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().

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= 924a9bc362a5223cd448ca08c3dde21235adc310, < 15583b07fd691a844fbf7b3ad612cdc9e9a657c0; >= 924a9bc362a5223cd448ca08c3dde21235adc310, < 8b444b126cd8e4473e652f529753ed4dd1360a9c; >= 924a9bc362a5223cd448ca08c3dde21235adc310, < 164c31ee252ebd1ac8f44c2dfc5486b6d9a0379b; >= 924a9bc362a5223cd448ca08c3dde21235adc310, < 3874892dd27d5387aa9a06f58d9060f18f351d24; ea3fb2ce5fa794d02135f5c079e05cd6fc3f545d; 54ef8243c3c8e90f1ea5792e6752e021a25c8eb3; ca278267d6cd9544645731732455b6b20cb0e895; faa3baa2828c5e1c4374f3e60041f75c64f5fcb6; 99b1d3f74b9ef72c2f74c8e4c078e1bc0706e748; >= 4.14.226, < 4.15; >= 4.19.181, < 4.20; >= 5.4.106, < 5.5; >= 5.10.24, < 5.11; >= 5.11.7, < 5.12
LinuxLinux5.12

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-74684?
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().
How severe is CVE-2026-74684?
Severity scoring for CVE-2026-74684 is pending analysis.
How do I fix CVE-2026-74684?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST