Medium [CVE-2026-72444] check device type before reading ETH_ADDRS
This medium-severity Red Hat Linux advisory covers CVE-2026-72444 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7.
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Summary
In the Linux kernel, the following vulnerability has been resolved: flow_dissector: check device type before reading ETH_ADDRS __skb_flow_dissect() unconditionally reads 12 bytes from eth_hdr(skb) when FLOW_DISSECTOR_KEY_ETH_ADDRS is requested. This assumes the skb has a valid Ethernet header at mac_header, which is not always the case.
The problem can be triggered by: 1. Creating a TUN device in L3 mode (IFF_TUN, hard_header_len=0) 2.
Attaching a multiq qdisc with a flower filter matching on eth_src 3. Sending a packet through AF_PACKET Since TUN in L3 mode has no link-layer header, mac_header points to the L3 data area.
The flow dissector reads 12 bytes of uninitialized skb memory, which then propagates through fl_set_masked_key() and is used as a rhashtable lookup key in __fl_lookup(), as reported by KMSAN.
Rejecting the filter in the control path (at tc filter add time) is not feasible because TC filter blocks can be shared between arbitrary devices -- a filter installed on an Ethernet device may later classify packets on a headerless device through a shared block.
Fix this by gating the memcpy on dev->type == ARPHRD_ETHER, which ensures only true Ethernet-framed packets have their addresses read.
Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; and 2 more.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source
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