# CVE-2024-26733: arp: Prevent overflow in arp_req_get().

> A buffer overflow in the Linux kernel ARP handler allows local attackers to corrupt memory, potentially causing crashes or privilege escalation.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 3 Apr 2024
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2024-26733, DEBIAN-CVE-2024-26733, GHSA-xqrq-q336-f78g, UBUNTU-CVE-2024-26733

## What is CVE-2024-26733?

CVE-2024-26733 is a medium-severity memory corruption vulnerability in Debian Debian Linux, published on 3 Apr 2024. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

arp: Prevent overflow in arp_req_get().

syzkaller reported an overflown write in arp_req_get(). [0]

When ioctl(SIOCGARP) is issued, arp_req_get() looks up an neighbour
entry and copies neigh->ha to struct arpreq.arp_ha.sa_data.

The arp_ha here is struct sockaddr, not struct sockaddr_storage, so
the sa_data buffer is just 14 bytes.

In the splat below, 2 bytes are overflown to the next int field,
arp_flags.  We initialise the field just after the memcpy(), so it's
not a problem.

However, when dev->addr_len is greater than 22 (e.g. MAX_ADDR_LEN),
arp_netmask is overwritten, which could be set as htonl(0xFFFFFFFFUL)
in arp_ioctl() before calling arp_req_get().

To avoid the overflow, let's limit the max length of memcpy().

Note that commit b5f0de6df6dc ("net: dev: Convert sa_data to flexible
array in struct sockaddr") just silenced syzkaller.

[0]:
memcpy: detected field-spanning write (size 16) of single field "r->arp_ha.sa_data" at net/ipv4/arp.c:1128 (size 14)
WARNING: CPU: 0 PID: 144638 at net/ipv4/arp.c:1128 arp_req_get+0x411/0x4a0 net/ipv4/arp.c:1128
Modules linked in:
CPU: 0 PID: 144638 Comm: syz-executor.4 Not tainted 6.1.74 #31
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-5 04/01/2014
RIP: 0010:arp_req_get+0x411/0x4a0 net/ipv4/arp.c:1128
Code: fd ff ff e8 41 42 de fb b9 0e 00 00 00 4c 89 fe 48 c7 c2 20 6d ab 87 48 c7 c7 80 6d ab 87 c6 05 25 af 72 04 01 e8 5f 8d ad fb <0f> 0b e9 6c fd ff ff e8 13 42 de fb be 03 00 00 00 4c 89 e7 e8 a6
RSP: 0018:ffffc900050b7998 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff88803a815000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8641a44a RDI: 0000000000000001
RBP: ffffc900050b7a98 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 203a7970636d656d R12: ffff888039c54000
R13: 1ffff92000a16f37 R14: ffff88803a815084 R15: 0000000000000010
FS:  00007f172bf306c0(0000) GS:ffff88805aa00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f172b3569f0 CR3: 0000000057f12005 CR4: 0000000000770ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
 <TASK>
 arp_ioctl+0x33f/0x4b0 net/ipv4/arp.c:1261
 inet_ioctl+0x314/0x3a0 net/ipv4/af_inet.c:981
 sock_do_ioctl+0xdf/0x260 net/socket.c:1204
 sock_ioctl+0x3ef/0x650 net/socket.c:1321
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __x64_sys_ioctl+0x18e/0x220 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x37/0x90 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x64/0xce
RIP: 0033:0x7f172b262b8d
Code: 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 f3 0f 1e fa 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:00007f172bf300b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f172b3abf80 RCX: 00007f172b262b8d
RDX: 0000000020000000 RSI: 0000000000008954 RDI: 0000000000000003
RBP: 00007f172b2d3493 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f172b3abf80 R15: 00007f172bf10000
 </TASK>

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2024-26733?

It affects 29 products.


Products: Debian Debian Linux, Linux kernel, Netapp 8200 Firmware, Netapp 8300 Firmware, Netapp 8700 Firmware, Netapp 9000 Firmware, Netapp 9500 Firmware, Netapp A150 Firmware, Netapp A1k Firmware, Netapp A220 Firmware, Netapp A300 Firmware, Netapp A320 Firmware, Netapp A400 Firmware, Netapp A700 Firmware, Netapp A700s Firmware, Netapp A70 Firmware, Netapp A800 Firmware, Netapp A900 Firmware, Netapp A90 Firmware, Netapp C190 Firmware and 9 more.

## How do I fix CVE-2024-26733?

Apply the vendor's patch.

## Is CVE-2024-26733 being exploited?

There is no known exploitation of CVE-2024-26733 in the wild and no public exploit code.

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## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-26733 and fix it if it is affected.

What it is: CVE-2024-26733 is a medium-severity memory corruption vulnerability in Debian Debian Linux, published on 3 Apr 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2024-26733 in the wild and no public exploit code.

Affected product: Debian Debian Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2024-26733/ (Markdown: https://insights.sbomify.com/CVE-2024-26733/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-26733
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-26733
- OSV: https://osv.dev/vulnerability/CVE-2024-26733

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-26733/
Summaries are generated and may contain mistakes; the official description above is the record.