---
cve: "CVE-2026-74561"
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: "2026-09-06T15:47:25+02:00"
---

# CVE-2026-74561

> 8.8 HIGH

## Beschreibung

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

nexthop: avoid unlocked f6i_list walk in nh_rt_cache_flush

nh_rt_cache_flush() walks nh->f6i_list during an RTNL-serialized nexthop
replace without holding nh->lock, racing the unlocked IPv6 route
add/delete that mutate the list under nh->lock and free fib6_info
entries (nh_rt_cache_flush() is inlined into rtm_new_nexthop()):

  BUG: KASAN: slab-use-after-free in nh_rt_cache_flush (net/ipv4/nexthop.c:2243)
  Read of size 8 at addr ffff888012953e18 by task exploit/146
   nh_rt_cache_flush (net/ipv4/nexthop.c:2243)
   replace_nexthop (net/ipv4/nexthop.c:2610)
   rtm_new_nexthop (net/ipv4/nexthop.c:3323)
   rtnetlink_rcv_msg (net/core/rtnetlink.c:7076)

Unlike the other f6i_list walks, this one bumps each route's sernum via
fib6_update_sernum_upto_root(), which needs tb6_lock; taking nh->lock
around it would invert the established tb6_lock -> nh->lock order and
deadlock. As the only purpose is to invalidate cached dsts, bump the
IPv6 sernum for the whole netns with rt_genid_bump_ipv6() instead,
mirroring the rt_cache_flush() already done for IPv4 just above.

## 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/44f53e4331a30fabc38a411fae7524341b618db3>
- <https://git.kernel.org/stable/c/4787a6d2629b4e8c0b6bacab1f75c1660eca44d9>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-74561) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_