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CVE-2026-74748

netfilter: ipset: fix refcount race between list:set GC and swap

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.266, 5.15.217, 6.1.184, 6.6.153, 6.12.105, and 2 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: total

Summary

In the Linux kernel, the following vulnerability has been resolved: netfilter: ipset: fix refcount race between list:set GC and swap __ip_set_put_byindex() resolved the index to a set pointer under RCU, then took ip_set_ref_lock in __ip_set_put() to decrement set->ref. ip_set_swap() holds that same lock while swapping both the ip_set_list slots and the two sets' ref counters, so it can interleave between the dereference and the lock acquisition, leaving the caller to decrement a set whose reference already moved to the other index and hit BUG_ON(set->ref == 0). list_set_gc() reaches this from timer softirq, which the nfnl mutex does not serialize against swap: an expiring list:set member calls list_set_del() -> ip_set_put_byindex() while IPSET_CMD_SWAP runs on the referenced sets. Resolve the index and decrement under ip_set_ref_lock, as ip_set_swap() already does, keeping the refcount tied to the index rather than to a stale set pointer. kernel BUG at net/netfilter/ipset/ip_set_core.c:685! Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI RIP: 0010:ip_set_put_byindex (net/netfilter/ipset/ip_set_core.c:870) Call Trace: <IRQ> list_set_del (net/netfilter/ipset/ip_set_list_set.c:159) set_cleanup_entries (net/netfilter/ipset/ip_set_list_set.c:181) list_set_gc (net/netfilter/ipset/ip_set_list_set.c:578) call_timer_fn (kernel/time/timer.c:1748) __run_timers (kernel/time/timer.c:1799 kernel/time/timer.c:2374) run_timer_softirq (kernel/time/timer.c:2405) </IRQ> Kernel panic - not syncing: Fatal exception in interrupt

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: total

  3. Record last updated

Affected versions

  • Linux Linux

    From 9076aea76538556224e7d73ab718f8841330818a · fixed in 97a01de0c6321b7210d30d0a4d60f10f561097c7; From 9076aea76538556224e7d73ab718f8841330818a · fixed in c21afc7c216a4d257a4f3f300e0791890bc846b9; From 9076aea76538556224e7d73ab718f8841330818a · fixed in b0aab9dd1a348b99d75ff52765719d0cc2050630; From 9076aea76538556224e7d73ab718f8841330818a · fixed in b891e7a6bb06e0f6560e5932665ac660acd12225; From 9076aea76538556224e7d73ab718f8841330818a · fixed in 20cb13a523f0a05cb2d0a7d72abae687683712e0; From 9076aea76538556224e7d73ab718f8841330818a · fixed in cb20da33839f28f590c99f16bafaa6151451c0e8; From 9076aea76538556224e7d73ab718f8841330818a · fixed in 24ffcb1e1688c55fd2a505f064295cd28eac546d; From 9076aea76538556224e7d73ab718f8841330818a · fixed in 0c88868271653537ed443272dd8e7d13634d214b

  • Linux Linux

    3.8

  • KernelLinux

    From 3.8.0 · fixed in 5.10.266; From 5.11.0 · fixed in 5.15.217; From 5.16.0 · fixed in 6.1.184; From 6.2.0 · fixed in 6.6.153; From 6.7.0 · fixed in 6.12.105; From 6.13.0 · fixed in 6.18.46; From 6.19.0 · fixed in 7.1.10

References 8

git.kernel.org