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Linux KernelOperating system · Linux

CVE-2024-40959

MEDIUM · 5.5 CVSS v3.1 Published 2024-07-12
Fix available
A fix is available. Upgrade to 4.19.317 / 5.4.279 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-476

The code follows a pointer that is null, crashing the process. An attacker who can reliably trigger it turns the crash into a denial of service. The fix is checking for null before use and handling the failure path gracefully.

General guidance for the null pointer dereference class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 2.6.12, < 4.19.317>= 4.20, < 5.4.279>= 5.5, < 5.10.221>= 5.11, < 5.15.162>= 5.16, < 6.1.96>= 6.2, < 6.6.36>= 6.7, < 6.9.7= 6.10

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 4.19.317 / 5.4.279 / 5.10.221 or later
Fixed in 4.19.3175.4.2795.10.221
Vendor patch git.kernel.org →
Recommended fix High confidence

Linux Kernel 4.19.317, 5.4.279, 5.10.221, or 5.15.162 (depending on your current branch)

  1. Identify your current Linux kernel version using `uname -r`
  2. Determine which affected branch your kernel falls into based on the version numbers
  3. For kernels < 4.19.317: upgrade to kernel 4.19.317 or later
  4. For kernels >= 4.20 and < 5.4.279: upgrade to kernel 5.4.279 or later
  5. For kernels >= 5.5 and < 5.10.221: upgrade to kernel 5.10.221 or later
  6. For kernels >= 5.11 and < 5.15.162: upgrade to kernel 5.15.162 or later
  7. After upgrading, verify the fix is present by checking the kernel source in net/ipv6/xfrm6_policy.c for the ip6_dst_idev() NULL check in xfrm6_get_saddr()
Caveat Kernel upgrades may require system reboot and could introduce compatibility issues with custom modules or older drivers; test in staging environment first

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $2,850. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2024-40959 in production — separate from our analysis above.

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What this is

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