---
cve: "CVE-2026-74562"
severity: "HIGH"
cvss: 8.8
epss: "11%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-08-15 13:18:01"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-02T21:11:52+02:00"
---

# CVE-2026-74562

> 8.8 HIGH

## Beschreibung

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

nexthop: take nh->lock for f6i_list walks in replace check and notify

fib6_check_nh_list() and __nexthop_replace_notify() walk nh->f6i_list
during an RTNL-serialized nexthop replace without holding nh->lock. IPv6
RTM_NEWROUTE/RTM_DELROUTE run without RTNL and mutate that list under
nh->lock (fib6_add_rt2node_nh(), fib6_purge_rt()), so both walks race a
concurrent route delete that unlinks and frees a fib6_info:

  BUG: KASAN: slab-use-after-free in rt6_fill_node.isra.0 (net/ipv6/route.c:5799)
  Read of size 4 at addr ffff888014607e64 by task exploit/143
   rt6_fill_node.isra.0 (net/ipv6/route.c:5799)
   fib6_rt_update (net/ipv6/route.c:6412)
   __nexthop_replace_notify (net/ipv4/nexthop.c:2542)
   rtm_new_nexthop (net/ipv4/nexthop.c:2554)
   rtnetlink_rcv_msg (net/core/rtnetlink.c:7076)

  BUG: KASAN: slab-use-after-free in fib6_check_nh_list (net/ipv4/nexthop.c:1605)
  Read of size 8 at addr ffff888014a7d068 by task exploit/142
   fib6_check_nh_list (net/ipv4/nexthop.c:1605)
   rtm_new_nexthop (net/ipv4/nexthop.c:2575)
   rtnetlink_rcv_msg (net/core/rtnetlink.c:7076)

Both walks only read the entries and take no tb6_lock, so protect them
with nh->lock; fib6_rt_update() uses gfp_any(), which returns GFP_ATOMIC
under the lock.

## CVSS-Vektor

```
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/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 | Verändert | bad |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- Kernel ≥ 7.1.8

## Referenzen

- <https://git.kernel.org/stable/c/bb2b072c619c1f741a6234257050f72005dc63ef>
- <https://git.kernel.org/stable/c/072cd1f21819dedd2252e704d255de3b0cfc61a7>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-74562) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_