High 8.8Published Aug 15, 2026

CVE-2026-74561nexthop: avoid unlocked f6i_list walk in nh_rt_cache_flush

Updated under an hour ago (2026-10-19 08:30 UTC)

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Exploited in the last 30 days

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: 8.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Received
Record last updated: Oct 15, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 081efd18326e353c6fbfdeff903a83edde953f72 before f97fae992155b11da516a509c855ff9d0868b107; 081efd18326e353c6fbfdeff903a83edde953f72 builds before 44f53e4331a30fabc38a411fae7524341b618db3; from 081efd18326e353c6fbfdeff903a83edde953f72 before 4787a6d2629b4e8c0b6bacab1f75c1660eca44d9	CNA record

References

https://git.kernel.org/stable/c/f97fae992155b11da516a509c855ff9d0868b107
https://git.kernel.org/stable/c/44f53e4331a30fabc38a411fae7524341b618db3
https://git.kernel.org/stable/c/4787a6d2629b4e8c0b6bacab1f75c1660eca44d9

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.