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Linux KernelOperating system · Linux

CVE-2023-53439

MEDIUM · 5.5 CVSS v3.1 Published 2025-09-18
Fix available
A fix is available. Upgrade to 6.1.30 / 6.3.4 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: net: skb_partial_csum_set() fix against transport header magic value skb->transport_header uses the special 0xFFFF value to mark if the transport header was set or not. We must prevent callers to accidentaly set skb->transport_header to 0xFFFF. Note that only fuzzers can possibly do this today. syzbot reported: WARNING: CPU: 0 PID: 2340 at include/linux/skbuff.h:2847 skb_transport_offset include/linux/skbuff.h:2956 [inline] WARNING: CPU: 0 PID: 2340 at include/linux/skbuff.h:2847 virtio_net_hdr_to_skb+0xbcc/0x10c0 include/linux/virtio_net.h:103 Modules linked in: CPU: 0 PID: 2340 Comm: syz-executor.0 Not tainted 6.3.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023 RIP: 0010:skb_transport_header include/linux/skbuff.h:2847 [inline] RIP: 0010:skb_transport_offset include/linux/skbuff.h:2956 [inline] RIP: 0010:virtio_net_hdr_to_skb+0xbcc/0x10c0 include/linux/virtio_net.h:103 Code: 41 39 df 0f 82 c3 04 00 00 48 8b 7c 24 10 44 89 e6 e8 08 6e 59 ff 48 85 c0 74 54 e8 ce 36 7e fc e9 37 f8 ff ff e8 c4 36 7e fc <0f> 0b e9 93 f8 ff ff 44 89 f7 44 89 e6 e8 32 38 7e fc 45 39 e6 0f RSP: 0018:ffffc90004497880 EFLAGS: 00010293 RAX: ffffffff84fea55c RBX: 000000000000ffff RCX: ffff888120be2100 RDX: 0000000000000000 RSI: 000000000000ffff RDI: 000000000000ffff RBP: ffffc90004497990 R08: ffffffff84fe9de5 R09: 0000000000000034 R10: ffffea00048ebd80 R11: 0000000000000034 R12: ffff88811dc2d9c8 R13: dffffc0000000000 R14: ffff88811dc2d9ae R15: 1ffff11023b85b35 FS: 00007f9211a59700(0000) GS:ffff8881f6c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000200002c0 CR3: 00000001215a5000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> packet_snd net/packet/af_packet.c:3076 [inline] packet_sendmsg+0x4590/0x61a0 net/packet/af_packet.c:3115 sock_sendmsg_nosec net/socket.c:724 [inline] sock_sendmsg net/socket.c:747 [inline] __sys_sendto+0x472/0x630 net/socket.c:2144 __do_sys_sendto net/socket.c:2156 [inline] __se_sys_sendto net/socket.c:2152 [inline] __x64_sys_sendto+0xe5/0x100 net/socket.c:2152 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2f/0x50 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f9210c8c169 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f9211a59168 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f9210dabf80 RCX: 00007f9210c8c169 RDX: 000000000000ffed RSI: 00000000200000c0 RDI: 0000000000000003 RBP: 00007f9210ce7ca1 R08: 0000000020000540 R09: 0000000000000014 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffe135d65cf R14: 00007f9211a59300 R15: 0000000000022000

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-401

Allocated memory is never released on some path, so a long-running service or a repeatedly triggered request steadily consumes memory until performance degrades or the process crashes. Attackers exploit it by simply driving the leaking path. Remediation is pairing every allocation with a release and using ownership patterns or tooling to catch what leaks.

General guidance for the memory leak 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:>= 5.19, < 6.1.30>= 6.2, < 6.3.4= 6.4

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 6.1.30 / 6.3.4 or later
Fixed in 6.1.306.3.4
Vendor patch git.kernel.org →
Recommended fix High confidence

Kernel 6.1.30+, 6.3.4+, or 6.5+ (depending on current branch)

  1. Check current running kernel version with 'uname -r'
  2. If running kernel 5.19 to < 6.1.30: upgrade to 6.1.30 or later in the 6.1.x stable branch
  3. If running kernel 6.2.x: upgrade to 6.3.4 or later in the 6.3.x stable branch
  4. If running kernel 6.4.x: upgrade to 6.5 or later stable branch
  5. Reboot the system to load the new kernel
  6. Verify the fix is applied by checking the kernel version and confirming the patch is present in /boot/config-* or via 'cat /proc/version'
Caveat Standard kernel upgrade risks apply - ensure compatibility with custom modules or drivers before upgrading

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 $1,600. 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-2023-53439 in production — separate from our analysis above.

No notes yet

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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