# CVE-2026-74561: linux: In the Linux kernel, the following vulnerability has been resolved:  nexthop: avoid unlocked f6i_list walk in nh_rt_c...

CVE-2026-74561 is fixed in linux on 1 platform by DEBIAN-CVE-2026-74561 (version 7.1.8-1), released August 16, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-74561
- Priority: High
- CVSS: 8.8 (high)
- EPSS: 0.0012
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 15, 2026

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 7.1.8-1 | [DEBIAN-CVE-2026-74561](https://patchblox.com/security/data/fix/linux/debian-cve-2026-74561.md) | Aug 16, 2026 |

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Data as of 2026-11-09T07:25:28Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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