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🛡️ CVE-2024-56646 — kernel

🟡 CVSS 5.5 — Medium ✅ No Known Exploit NVD
5.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

ipv6: avoid possible NULL deref in modify_prefix_route()

In the Linux kernel, the following vulnerability has been resolved:

ipv6: avoid possible NULL deref in modify_prefix_route()

syzbot found a NULL deref [1] in modify_prefix_route(), caused by one

fib6_info without a fib6_table pointer set.

This can happen for net->ipv6.fib6_null_entry

[1]

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] PREEMPT SMP KASAN NOPTI

KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037]

CPU: 1 UID: 0 PID: 5837 Comm: syz-executor888 Not tainted 6.12.0-syzkaller-09567-g7eef7e306d3c #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024

RIP: 0010:__lock_acquire+0xe4/0x3c40 kernel/locking/lockdep.c:5089

Code: 08 84 d2 0f 85 15 14 00 00 44 8b 0d ca 98 f5 0e 45 85 c9 0f 84 b4 0e 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00 0f 85 96 2c 00 00 49 8b 04 24 48 3d a0 07 7f 93 0f 84

RSP: 0018:ffffc900035d7268 EFLAGS: 00010006

RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000

RDX: 0000000000000006 RSI: 1ffff920006bae5f RDI: 0000000000000030

RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001

R10: ffffffff90608e17 R11: 0000000000000001 R12: 0000000000000030

R13: ffff888036334880 R14: 0000000000000000 R15: 0000000000000000

FS: 0000555579e90380(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007ffc59cc4278 CR3: 0000000072b54000 CR4: 00000000003526f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000

DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Call Trace:

<TASK>

lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849

__raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]

_raw_spin_lock_bh+0x33/0x40 kernel/locking/spinlock.c:178

spin_lock_bh include/linux/spinlock.h:356 [inline]

modify_prefix_route+0x30b/0x8b0 net/ipv6/addrconf.c:4831

inet6_addr_modify net/ipv6/addrconf.c:4923 [inline]

inet6_rtm_newaddr+0x12c7/0x1ab0 net/ipv6/addrconf.c:5055

rtnetlink_rcv_msg+0x3c7/0xea0 net/core/rtnetlink.c:6920

netlink_rcv_skb+0x16b/0x440 net/netlink/af_netlink.c:2541

netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline]

netlink_unicast+0x53c/0x7f0 net/netlink/af_netlink.c:1347

netlink_sendmsg+0x8b8/0xd70 net/netlink/af_netlink.c:1891

sock_sendmsg_nosec net/socket.c:711 [inline]

__sock_sendmsg net/socket.c:726 [inline]

____sys_sendmsg+0xaaf/0xc90 net/socket.c:2583

___sys_sendmsg+0x135/0x1e0 net/socket.c:2637

__sys_sendmsg+0x16e/0x220 net/socket.c:2669

do_syscall_x64 arch/x86/entry/common.c:52 [inline]

do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83

entry_SYSCALL_64_after_hwframe+0x77/0x7f

RIP: 0033:0x7fd1dcef8b79

Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 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:00007ffc59cc4378 EFLAGS: 00000246 ORIG_RAX: 000000000000002e

RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fd1dcef8b79

RDX: 0000000000040040 RSI: 0000000020000140 RDI: 0000000000000004

RBP: 00000000000113fd R08: 0000000000000006 R09: 0000000000000006

R10: 0000000000000006 R11: 0000000000000246 R12: 00007ffc59cc438c

R13: 431bde82d7b634db R14: 0000000000000001 R15: 0000000000000001

</TASK>

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

  • Attack vector: Local — a local account, shell or session on the host is needed.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: Low — an ordinary user account is enough.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: None.
  • Integrity impact: None.
  • Availability impact: High — total loss, or loss the attacker controls.

Affected software

CVE-2024-56646 is recorded against 2 packages.

  • kernel (from 6.9.0 up to 6.12.5)
  • linux-kernel

Timeline and source

Published on 27 December 2024 and last revised on 12 August 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
github.com (Advisory)
nvd.nist.gov (Advisory)
git.kernel.org (Package)

Other advisories for this package

kernel has other advisories on record. If you are patching this one, these are worth checking on the same host:

CVE-2024-56646 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Medium
CVSS Score 5.5
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2024-12-27
Updated 2026-08-20
Modified 2026-08-12

Affected Packages

Software From version Fixed in
kernel 6.9.0 6.12.5
linux-kernel — —

Similar Threats

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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