Medium 5.5Published Feb 14, 2026

CVE-2026-23124ipv6: annotate data-race in ndisc_router_discovery()

Updated under an hour ago (Oct 26, 2026, 1:00 PM ET)

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Exploited in the last 30 days

In the Linux kernel, the following vulnerability has been resolved: ipv6: annotate data-race in ndisc_router_discovery() syzbot found that ndisc_router_discovery() could read and write in6_dev->ra_mtu without holding a lock [1] This looks fine, IFLA_INET6_RA_MTU is best effort. Add READ_ONCE()/WRITE_ONCE() to document the race. Note that we might also reject illegal MTU values (mtu < IPV6_MIN_MTU || mtu > skb->dev->mtu) in a future patch. [1] BUG: KCSAN: data-race in ndisc_router_discovery / ndisc_router_discovery read to 0xffff888119809c20 of 4 bytes by task 25817 on cpu 1: ndisc_router_discovery+0x151d/0x1c90 net/ipv6/ndisc.c:1558 ndisc_rcv+0x2ad/0x3d0 net/ipv6/ndisc.c:1841 icmpv6_rcv+0xe5a/0x12f0 net/ipv6/icmp.c:989 ip6_protocol_deliver_rcu+0xb2a/0x10d0 net/ipv6/ip6_input.c:438 ip6_input_finish+0xf0/0x1d0 net/ipv6/ip6_input.c:489 NF_HOOK include/linux/netfilter.h:318 [inline] ip6_input+0x5e/0x140 net/ipv6/ip6_input.c:500 ip6_mc_input+0x27c/0x470 net/ipv6/ip6_input.c:590 dst_input include/net/dst.h:474 [inline] ip6_rcv_finish+0x336/0x340 net/ipv6/ip6_input.c:79 ... write to 0xffff888119809c20 of 4 bytes by task 25816 on cpu 0: ndisc_router_discovery+0x155a/0x1c90 net/ipv6/ndisc.c:1559 ndisc_rcv+0x2ad/0x3d0 net/ipv6/ndisc.c:1841 icmpv6_rcv+0xe5a/0x12f0 net/ipv6/icmp.c:989 ip6_protocol_deliver_rcu+0xb2a/0x10d0 net/ipv6/ip6_input.c:438 ip6_input_finish+0xf0/0x1d0 net/ipv6/ip6_input.c:489 NF_HOOK include/linux/netfilter.h:318 [inline] ip6_input+0x5e/0x140 net/ipv6/ip6_input.c:500 ip6_mc_input+0x27c/0x470 net/ipv6/ip6_input.c:590 dst_input include/net/dst.h:474 [inline] ip6_rcv_finish+0x336/0x340 net/ipv6/ip6_input.c:79 ... value changed: 0x00000000 -> 0xe5400659

CVSS: 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-362
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: Modified
Record last updated: Oct 19, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7 before 4630897eb1a039b5d7b737b8dc9521d9d4b568b5; from 49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7 before 2619499169fb1c2ac4974b0f2d87767fb543582b; from 49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7 before fad8f4ff7928f4d52a062ffdcffa484989c79c47; 49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7 builds before 2a2b9d25f801afecf2f83cacce98afa8fd73e3c9; from 49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7 before e3c1040252e598f7b4e33a42dc7c38519bc22428; 49b99da2c9ce13ffcd93fe3a0f5670791c1d76f7 builds before 9a063f96d87efc3a6cc667f8de096a3d38d74bb5	CNA record
linux linux_kernel linux:linux_kernel	from 5.15 before 5.15.199; from 5.16 before 6.1.162; from 6.2 before 6.6.122; from 6.7 before 6.12.68; from 6.13 before 6.18.8; 6.19; 6.19; 6.19; and 3 more ranges	NVD

References

References

https://git.kernel.org/stable/c/4630897eb1a039b5d7b737b8dc9521d9d4b568b5	patch
https://git.kernel.org/stable/c/2619499169fb1c2ac4974b0f2d87767fb543582b	patch
https://git.kernel.org/stable/c/fad8f4ff7928f4d52a062ffdcffa484989c79c47	patch
https://git.kernel.org/stable/c/2a2b9d25f801afecf2f83cacce98afa8fd73e3c9	patch
https://git.kernel.org/stable/c/e3c1040252e598f7b4e33a42dc7c38519bc22428	patch
https://git.kernel.org/stable/c/9a063f96d87efc3a6cc667f8de096a3d38d74bb5	patch

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.