Bug 2517017 (CVE-2026-74474)

Summary: CVE-2026-74474 kernel: vxlan: use pskb_network_may_pull() for transmit path header pulls
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's vxlan module. This vulnerability arises from the incorrect handling of network packet headers during data transmission. Specifically, certain functions within the vxlan module fail to properly account for the initial part of the network packet, known as the Media Access Control (MAC) header. This oversight can lead to fragmented network header information, potentially causing unexpected network behavior or data processing errors.
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Description OSIDB Bzimport 2026-08-15 12:45:04 UTC 
In the Linux kernel, the following vulnerability has been resolved:

vxlan: use pskb_network_may_pull() for transmit path header pulls

In vxlan_xmit(), arp_reduce(), and vxlan_mdb_entry_skb_get(), pskb_may_pull() was
being called to verify the availability of network layer headers (ARP, IPv6/ND,
IP/IPv6 MDB keys).

However, during transmit skb->data points to the MAC header, so skb_network_offset(skb)
is ETH_HLEN (14 bytes). Using pskb_may_pull(skb, len) only checks len bytes from skb->data
rather than skb_network_offset(skb) + len, which can leave part of the network header
in non-linear frags.

Replace these remaining pskb_may_pull() calls with pskb_network_may_pull() to properly
account for the MAC header offset.
Comment 1 Mauro Matteo Cascella 2026-08-21 08:34:06 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081535-CVE-2026-74474-e720@gregkh/T