CVE-2026-74695 PUBLISHED

netfilter: nf_flow_table: drop existing skb dst before skb_dst_set_noref()

Assigner: Linux
Reserved: 15.08.2026 Published: 22.08.2026 Updated: 22.08.2026

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nf_flow_table: drop existing skb dst before skb_dst_set_noref()

Incoming skbs passing through netfilter flowtable offload hooks (or XFRM offload path) might already carry a ref-counted dst_entry assigned during earlier RX or routing steps.

Calling skb_dst_set_noref() when skb already holds a ref-counted dst overwrites skb->_skb_refdst, leaking the previous dst_entry reference count and triggering a DEBUG_NET_WARN_ON_ONCE assertion in skb_dst_check_unset():

WARNING: at skb_dst_check_unset include/linux/skbuff.h:1170 WARNING: at skb_dst_set_noref include/linux/skbuff.h:1234 WARNING: at nf_flow_offload_ip_hook+0xf6c/0x2b60 net/netfilter/nf_flow_table_ip.c:864

Drop any existing dst_entry reference with skb_dst_drop(skb) before setting the non-referenced flowtable destination.

Product Status

Vendor Linux
Product Linux
Versions Default: unaffected
  • affected from 2a79fd3908acd88e6cb0e620c314d7b1fee56a02 to 12afa450a6a6c0cce2c42b7545a9958f62d8a00c (excl.)
  • affected from 2a79fd3908acd88e6cb0e620c314d7b1fee56a02 to 538e67e8c7889cf5f93951f5309d1bcb41f86036 (excl.)
  • affected from 2a79fd3908acd88e6cb0e620c314d7b1fee56a02 to 8aecf0bbcc72605592134c917c222207d8f63ab0 (excl.)
  • Version b4b1adf2e66ecc7125c4117e7aad9ff61e2cfd27 is affected
  • Version 209dedf806d31095968f54323dbe62525b077b33 is affected
  • affected from 4.16.15 to 4.17 (excl.)
  • affected from 4.17.1 to 4.18 (excl.)
Vendor Linux
Product Linux
Versions Default: affected
  • Version 4.18 is affected
  • unaffected from 0 to 4.18 (excl.)
  • unaffected from 6.18.45 to 6.18.* (incl.)
  • unaffected from 7.1.9 to 7.1.* (incl.)
  • unaffected from 7.2 to * (incl.)

References