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Linux KernelOperating system · Linux

CVE-2024-27018

HIGH · 7.8 CVSS v3.1 Published 2024-05-01
Fix available
A fix is available. Upgrade to 5.15.157 / 6.1.88 or later.
See remediation →
80/100
Remediation priority · High
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: netfilter: br_netfilter: skip conntrack input hook for promisc packets For historical reasons, when bridge device is in promisc mode, packets that are directed to the taps follow bridge input hook path. This patch adds a workaround to reset conntrack for these packets. Jianbo Liu reports warning splats in their test infrastructure where cloned packets reach the br_netfilter input hook to confirm the conntrack object. Scratch one bit from BR_INPUT_SKB_CB to annotate that this packet has reached the input hook because it is passed up to the bridge device to reach the taps. [ 57.571874] WARNING: CPU: 1 PID: 0 at net/bridge/br_netfilter_hooks.c:616 br_nf_local_in+0x157/0x180 [br_netfilter] [ 57.572749] Modules linked in: xt_MASQUERADE nf_conntrack_netlink nfnetlink iptable_nat xt_addrtype xt_conntrack nf_nat br_netfilter rpcsec_gss_krb5 auth_rpcgss oid_registry overlay rpcrdma rdma_ucm ib_iser libiscsi scsi_transport_isc si ib_umad rdma_cm ib_ipoib iw_cm ib_cm mlx5_ib ib_uverbs ib_core mlx5ctl mlx5_core [ 57.575158] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.8.0+ #19 [ 57.575700] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 [ 57.576662] RIP: 0010:br_nf_local_in+0x157/0x180 [br_netfilter] [ 57.577195] Code: fe ff ff 41 bd 04 00 00 00 be 04 00 00 00 e9 4a ff ff ff be 04 00 00 00 48 89 ef e8 f3 a9 3c e1 66 83 ad b4 00 00 00 04 eb 91 <0f> 0b e9 f1 fe ff ff 0f 0b e9 df fe ff ff 48 89 df e8 b3 53 47 e1 [ 57.578722] RSP: 0018:ffff88885f845a08 EFLAGS: 00010202 [ 57.579207] RAX: 0000000000000002 RBX: ffff88812dfe8000 RCX: 0000000000000000 [ 57.579830] RDX: ffff88885f845a60 RSI: ffff8881022dc300 RDI: 0000000000000000 [ 57.580454] RBP: ffff88885f845a60 R08: 0000000000000001 R09: 0000000000000003 [ 57.581076] R10: 00000000ffff1300 R11: 0000000000000002 R12: 0000000000000000 [ 57.581695] R13: ffff8881047ffe00 R14: ffff888108dbee00 R15: ffff88814519b800 [ 57.582313] FS: 0000000000000000(0000) GS:ffff88885f840000(0000) knlGS:0000000000000000 [ 57.583040] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 57.583564] CR2: 000000c4206aa000 CR3: 0000000103847001 CR4: 0000000000370eb0 [ 57.584194] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 57.584820] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 57.585440] Call Trace: [ 57.585721] <IRQ> [ 57.585976] ? __warn+0x7d/0x130 [ 57.586323] ? br_nf_local_in+0x157/0x180 [br_netfilter] [ 57.586811] ? report_bug+0xf1/0x1c0 [ 57.587177] ? handle_bug+0x3f/0x70 [ 57.587539] ? exc_invalid_op+0x13/0x60 [ 57.587929] ? asm_exc_invalid_op+0x16/0x20 [ 57.588336] ? br_nf_local_in+0x157/0x180 [br_netfilter] [ 57.588825] nf_hook_slow+0x3d/0xd0 [ 57.589188] ? br_handle_vlan+0x4b/0x110 [ 57.589579] br_pass_frame_up+0xfc/0x150 [ 57.589970] ? br_port_flags_change+0x40/0x40 [ 57.590396] br_handle_frame_finish+0x346/0x5e0 [ 57.590837] ? ipt_do_table+0x32e/0x430 [ 57.591221] ? br_handle_local_finish+0x20/0x20 [ 57.591656] br_nf_hook_thresh+0x4b/0xf0 [br_netfilter] [ 57.592286] ? br_handle_local_finish+0x20/0x20 [ 57.592802] br_nf_pre_routing_finish+0x178/0x480 [br_netfilter] [ 57.593348] ? br_handle_local_finish+0x20/0x20 [ 57.593782] ? nf_nat_ipv4_pre_routing+0x25/0x60 [nf_nat] [ 57.594279] br_nf_pre_routing+0x24c/0x550 [br_netfilter] [ 57.594780] ? br_nf_hook_thresh+0xf0/0xf0 [br_netfilter] [ 57.595280] br_handle_frame+0x1f3/0x3d0 [ 57.595676] ? br_handle_local_finish+0x20/0x20 [ 57.596118] ? br_handle_frame_finish+0x5e0/0x5e0 [ 57.596566] __netif_receive_skb_core+0x25b/0xfc0 [ 57.597017] ? __napi_build_skb+0x37/0x40 [ 57.597418] __netif_receive_skb_list_core+0xfb/0x220

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

A detailed technical summary for this CVE is being prepared.

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:>= 5.15.151, < 5.15.157>= 6.1.81, < 6.1.88>= 6.6.21, < 6.6.29>= 6.7.9, < 6.8.8= 6.9
FedoraOperating system
Affected:= 38= 39= 40

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
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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 5.15.157 / 6.1.88 / 6.6.29 or later
Fixed in 5.15.1576.1.886.6.29
Vendor patch git.kernel.org →
Recommended fix High confidence

Kernel 5.15.157, 6.1.88, 6.6.29, or 6.8.8 (or later stable release) - Fedora users should update to latest available kernel via dnf

  1. Identify your current kernel version using 'uname -r' or 'cat /proc/version'
  2. For mainline Linux: Upgrade to kernel version 5.15.157, 6.1.88, 6.6.29, or 6.8.8 (or later) depending on your base version branch
  3. For Fedora systems: Run 'sudo dnf update' to fetch and install the latest kernel package that includes the fix for CVE-2024-27018
  4. Reboot the system to load the new kernel: 'sudo systemctl reboot'
  5. Verify the fix is applied by checking the running kernel version with 'uname -r' and confirming it is >= the fixed version for your branch
Caveat Kernel upgrades are generally safe but may require rebuilding third-party kernel modules; ensure critical modules are compatible with the new kernel version

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 $1,950. 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

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