Bug 2521401 (CVE-2026-74701) - CVE-2026-74701 kernel: net/openvswitch: check Ethernet header length in key_extract()
Summary: CVE-2026-74701 kernel: net/openvswitch: check Ethernet header length in key_e...
Keywords:
Status: NEW
Alias: CVE-2026-74701
Product: Security Response
Classification: Other
Component: vulnerability-draft
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-08-22 15:43 UTC by OSIDB Bzimport
Modified: 2026-08-24 11:22 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
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Description OSIDB Bzimport 2026-08-22 15:43:44 UTC
In the Linux kernel, the following vulnerability has been resolved:

net/openvswitch: check Ethernet header length in key_extract()

When a packet arrives on an ARPHRD_NONE device (e.g. TUN),
ovs_flow_key_extract() trusts the user-provided skb->protocol field: if
it is ETH_P_TEB, the packet is classified as MAC_PROTO_ETHERNET and
key_extract() is called without ensuring the skb has ETH_HLEN (14) bytes
of linear data. key_extract() unconditionally pulls 2 * ETH_ALEN bytes
for MAC addresses and parse_ethertype() pulls 2 more, either of which
triggers a kernel BUG in __skb_pull() when the linear area is too small.

  kernel BUG at include/linux/skbuff.h:2848!
  RIP: 0010:key_extract+0xa7e/0xd90 net/openvswitch/flow.c:933
  ovs_flow_key_extract+0x419/0xa70
  ovs_vport_receive+0x222/0x390
  netdev_frame_hook+0x3e0/0x630
  tun_get_user+0x2d0c/0x38e0

Fixed by calling check_header() in key_extract() before accessing the
Ethernet header.

Comment 1 Mauro Matteo Cascella 2026-08-24 11:15:10 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026082235-CVE-2026-74701-282b@gregkh/T


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