{"id":"CVE-2025-38638","state":"PUBLISHED","title":"ipv6: add a retry logic in net6_rt_notify()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: add a retry logic in net6_rt_notify()\n\ninet6_rt_notify() can be called under RCU protection only.\nThis means the route could be changed concurrently\nand rt6_fill_node() could return -EMSGSIZE.\n\nRe-size the skb when this happens and retry, removing\none WARN_ON() that syzbot was able to trigger:\n\nWARNING: CPU: 3 PID: 6291 at net/ipv6/route.c:6342 inet6_rt_notify+0x475/0x4b0 net/ipv6/route.c:6342\nModules linked in:\nCPU: 3 UID: 0 PID: 6291 Comm: syz.0.77 Not tainted 6.16.0-rc7-syzkaller #0 PREEMPT(full)\nHardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014\n RIP: 0010:inet6_rt_notify+0x475/0x4b0 net/ipv6/route.c:6342\nCode: fc ff ff e8 6d 52 ea f7 e9 47 fc ff ff 48 8b 7c 24 08 4c 89 04 24 e8 5a 52 ea f7 4c 8b 04 24 e9 94 fd ff ff e8 9c fe 84 f7 90 <0f> 0b 90 e9 bd fd ff ff e8 6e 52 ea f7 e9 bb fb ff ff 48 89 df e8\nRSP: 0018:ffffc900035cf1d8 EFLAGS: 00010293\nRAX: 0000000000000000 RBX: ffffc900035cf540 RCX: ffffffff8a36e790\nRDX: ffff88802f7e8000 RSI: ffffffff8a36e9d4 RDI: 0000000000000005\nRBP: ffff88803c230f00 R08: 0000000000000005 R09: 00000000ffffffa6\nR10: 00000000ffffffa6 R11: 0000000000000001 R12: 00000000ffffffa6\nR13: 0000000000000900 R14: ffff888032ea4100 R15: 0000000000000000\nFS:  00007fac7b89a6c0(0000) GS:ffff8880d6a20000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00007fac7b899f98 CR3: 0000000034b3f000 CR4: 0000000000352ef0\nCall Trace:\n <TASK>\n  ip6_route_mpath_notify+0xde/0x280 net/ipv6/route.c:5356\n  ip6_route_multipath_add+0x1181/0x1bd0 net/ipv6/route.c:5536\n  inet6_rtm_newroute+0xe4/0x1a0 net/ipv6/route.c:5647\n  rtnetlink_rcv_msg+0x95e/0xe90 net/core/rtnetlink.c:6944\n  netlink_rcv_skb+0x155/0x420 net/netlink/af_netlink.c:2552\n  netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]\n  netlink_unicast+0x58d/0x850 net/netlink/af_netlink.c:1346\n  netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1896\n  sock_sendmsg_nosec net/socket.c:712 [inline]\n  __sock_sendmsg net/socket.c:727 [inline]\n  ____sys_sendmsg+0xa95/0xc70 net/socket.c:2566\n  ___sys_sendmsg+0x134/0x1d0 net/socket.c:2620","publishedAt":"2025-08-22T16:00:44.913Z","updatedAt":"2026-05-11T21:32:05.569Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"169fd62799e8acabbfb4760799be11138ced949c","status":"affected","lessThan":"0bdca3439a22c70eb8f404acd61bf7aca5d731b0","versionType":"git"},{"version":"169fd62799e8acabbfb4760799be11138ced949c","status":"affected","lessThan":"ea2f921db7a483a526058c5b5b8162edd88dabe5","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/route.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.16","versionType":"semver"},{"version":"6.16.1","status":"unaffected","lessThanOrEqual":"6.16.*","versionType":"semver"},{"version":"6.17","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/route.c"]}],"references":["https://git.kernel.org/stable/c/0bdca3439a22c70eb8f404acd61bf7aca5d731b0","https://git.kernel.org/stable/c/ea2f921db7a483a526058c5b5b8162edd88dabe5"],"weaknesses":[],"ingestedAt":"2026-10-29T20:09:09.358Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/38xxx/CVE-2025-38638.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-38638","state":"PUBLISHED","datePublished":"2025-08-22T16:00:44.913Z","dateUpdated":"2026-05-11T21:32:05.569Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-04-16T04:51:24.030Z"},"containers":{"cna":{"title":"ipv6: add a retry logic in net6_rt_notify()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: add a retry logic in net6_rt_notify()\n\ninet6_rt_notify() can be called under RCU protection only.\nThis means the route could be changed concurrently\nand rt6_fill_node() could return -EMSGSIZE.\n\nRe-size the skb when this happens and retry, removing\none WARN_ON() that syzbot was able to trigger:\n\nWARNING: CPU: 3 PID: 6291 at net/ipv6/route.c:6342 inet6_rt_notify+0x475/0x4b0 net/ipv6/route.c:6342\nModules linked in:\nCPU: 3 UID: 0 PID: 6291 Comm: syz.0.77 Not tainted 6.16.0-rc7-syzkaller #0 PREEMPT(full)\nHardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014\n RIP: 0010:inet6_rt_notify+0x475/0x4b0 net/ipv6/route.c:6342\nCode: fc ff ff e8 6d 52 ea f7 e9 47 fc ff ff 48 8b 7c 24 08 4c 89 04 24 e8 5a 52 ea f7 4c 8b 04 24 e9 94 fd ff ff e8 9c fe 84 f7 90 <0f> 0b 90 e9 bd fd ff ff e8 6e 52 ea f7 e9 bb fb ff ff 48 89 df e8\nRSP: 0018:ffffc900035cf1d8 EFLAGS: 00010293\nRAX: 0000000000000000 RBX: ffffc900035cf540 RCX: ffffffff8a36e790\nRDX: ffff88802f7e8000 RSI: ffffffff8a36e9d4 RDI: 0000000000000005\nRBP: ffff88803c230f00 R08: 0000000000000005 R09: 00000000ffffffa6\nR10: 00000000ffffffa6 R11: 0000000000000001 R12: 00000000ffffffa6\nR13: 0000000000000900 R14: ffff888032ea4100 R15: 0000000000000000\nFS:  00007fac7b89a6c0(0000) GS:ffff8880d6a20000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00007fac7b899f98 CR3: 0000000034b3f000 CR4: 0000000000352ef0\nCall Trace:\n <TASK>\n  ip6_route_mpath_notify+0xde/0x280 net/ipv6/route.c:5356\n  ip6_route_multipath_add+0x1181/0x1bd0 net/ipv6/route.c:5536\n  inet6_rtm_newroute+0xe4/0x1a0 net/ipv6/route.c:5647\n  rtnetlink_rcv_msg+0x95e/0xe90 net/core/rtnetlink.c:6944\n  netlink_rcv_skb+0x155/0x420 net/netlink/af_netlink.c:2552\n  netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]\n  netlink_unicast+0x58d/0x850 net/netlink/af_netlink.c:1346\n  netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1896\n  sock_sendmsg_nosec net/socket.c:712 [inline]\n  __sock_sendmsg net/socket.c:727 [inline]\n  ____sys_sendmsg+0xa95/0xc70 net/socket.c:2566\n  ___sys_sendmsg+0x134/0x1d0 net/socket.c:2620"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"169fd62799e8acabbfb4760799be11138ced949c","status":"affected","lessThan":"0bdca3439a22c70eb8f404acd61bf7aca5d731b0","versionType":"git"},{"version":"169fd62799e8acabbfb4760799be11138ced949c","status":"affected","lessThan":"ea2f921db7a483a526058c5b5b8162edd88dabe5","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/route.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.16","versionType":"semver"},{"version":"6.16.1","status":"unaffected","lessThanOrEqual":"6.16.*","versionType":"semver"},{"version":"6.17","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/route.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/0bdca3439a22c70eb8f404acd61bf7aca5d731b0"},{"url":"https://git.kernel.org/stable/c/ea2f921db7a483a526058c5b5b8162edd88dabe5"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T21:32:05.569Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.16","versionEndExcluding":"6.16.1"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.16","versionEndExcluding":"6.17"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}