---
cve: "CVE-2026-74667"
severity: "HIGH"
cvss: 7.8
epss: "26.6%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-08-22 16:16:40"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-08T17:09:21+02:00"
---

# CVE-2026-74667

> 7.8 HIGH

## Beschreibung

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

net/packet: reset the MAC header on the packet-socket transmit path

packet_parse_headers() resets the MAC header only for a SOCK_RAW frame
whose socket did not bind a protocol. A protocol-bound SOCK_RAW socket,
any SOCK_DGRAM frame, and the legacy SOCK_PACKET path therefore leave
skb->mac_header unset here.

For frames sent via __dev_queue_xmit() this is harmless: it resets the
MAC header unconditionally. But the packet-socket PACKET_QDISC_BYPASS
path uses dev_direct_xmit(), which does not, so the frame reaches
ndo_start_xmit() with the MAC header unset. A driver that reads
eth_hdr(skb) on transmit then dereferences skb->head + (u16)~0, an
out-of-bounds access ~64 KiB past the head -- the same class fixed for
one consumer in commit f5089008f90c ("macsec: do not read an unset MAC
header in macsec_encrypt()").

packet_parse_headers() runs only on the transmit path, where skb->data
points at the start of the L2 header for every packet-socket type
regardless of its length: SOCK_RAW and SOCK_PACKET carry a user-supplied
header and SOCK_DGRAM has one built by dev_hard_header(). Reset the MAC
header unconditionally, mirroring __dev_queue_xmit(), so the frame is
anchored on the bypass path too.

Found by 0sec (https://0sec.ai) using automated source analysis;
verified against source and matched to the macsec KASAN report in
f5089008f90c. Compile-tested.

## CVSS-Vektor

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

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Lokal | good |
| AC Komplexität | Gering | bad |
| PR Privilegien | Gering | warn |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- Kernel ≥ 5.10.265
- Kernel ≥ 5.15.216
- Kernel ≥ 6.1.183
- Kernel ≥ 6.6.152
- Kernel ≥ 6.12.104
- Kernel ≥ 6.18.45
- Kernel ≥ 7.1.9

## Referenzen

- <https://git.kernel.org/stable/c/1e43a1d66615f411d427f9df1f46dd049d9e3681>
- <https://git.kernel.org/stable/c/2610ed4e86a4590234a9d70518c469751c5af231>
- <https://git.kernel.org/stable/c/284f3e7a3f1a743fdf89e304fd1f19d5ffcff46d>
- <https://git.kernel.org/stable/c/4057853a91fb796c4f47c7d1baf1aa085394148e>
- <https://git.kernel.org/stable/c/971aa7d99242bbf09513e27b7a243f0b29ff23ae>
- <https://git.kernel.org/stable/c/b47ba8fe6e1d2df8c92048de5afafd059447dc30>
- <https://git.kernel.org/stable/c/c2707480cfbf19c7619acc9c089d17f20869821f>
- <https://git.kernel.org/stable/c/fdd4d7d52358a58e351dd9d82530c04eba8ccd7a>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-74667) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_