{"cve":"CVE-2025-38622","nvd":{"published":"2025-08-22T16:15:35.603","modified":"2026-06-17T09:17:14.090","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: drop UFO packets in udp_rcv_segment()\n\nWhen sending a packet with virtio_net_hdr to tun device, if the gso_type\nin virtio_net_hdr is SKB_GSO_UDP and the gso_size is less than udphdr\nsize, below crash may happen.\n\n  ------------[ cut here ]------------\n  kernel BUG at net/core/skbuff.c:4572!\n  Oops: invalid opcode: 0000 [#1] SMP NOPTI\n  CPU: 0 UID: 0 PID: 62 Comm: mytest Not tainted 6.16.0-rc7 #203 PREEMPT(voluntary)\n  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014\n  RIP: 0010:skb_pull_rcsum+0x8e/0xa0\n  Code: 00 00 5b c3 cc cc cc cc 8b 93 88 00 00 00 f7 da e8 37 44 38 00 f7 d8 89 83 88 00 00 00 48 8b 83 c8 00 00 00 5b c3 cc cc cc cc <0f> 0b 0f 0b 66 66 2e 0f 1f 84 00 000\n  RSP: 0018:ffffc900001fba38 EFLAGS: 00000297\n  RAX: 0000000000000004 RBX: ffff8880040c1000 RCX: ffffc900001fb948\n  RDX: ffff888003e6d700 RSI: 0000000000000008 RDI: ffff88800411a062\n  RBP: ffff8880040c1000 R08: 0000000000000000 R09: 0000000000000001\n  R10: ffff888003606c00 R11: 0000000000000001 R12: 0000000000000000\n  R13: ffff888004060900 R14: ffff888004050000 R15: ffff888004060900\n  FS:  000000002406d3c0(0000) GS:ffff888084a19000(0000) knlGS:0000000000000000\n  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n  CR2: 0000000020000040 CR3: 0000000004007000 CR4: 00000000000006f0\n  Call Trace:\n   <TASK>\n   udp_queue_rcv_one_skb+0x176/0x4b0 net/ipv4/udp.c:2445\n   udp_queue_rcv_skb+0x155/0x1f0 net/ipv4/udp.c:2475\n   udp_unicast_rcv_skb+0x71/0x90 net/ipv4/udp.c:2626\n   __udp4_lib_rcv+0x433/0xb00 net/ipv4/udp.c:2690\n   ip_protocol_deliver_rcu+0xa6/0x160 net/ipv4/ip_input.c:205\n   ip_local_deliver_finish+0x72/0x90 net/ipv4/ip_input.c:233\n   ip_sublist_rcv_finish+0x5f/0x70 net/ipv4/ip_input.c:579\n   ip_sublist_rcv+0x122/0x1b0 net/ipv4/ip_input.c:636\n   ip_list_rcv+0xf7/0x130 net/ipv4/ip_input.c:670\n   __netif_receive_skb_list_core+0x21d/0x240 net/core/dev.c:6067\n   netif_receive_skb_list_internal+0x186/0x2b0 net/core/dev.c:6210\n   napi_complete_done+0x78/0x180 net/core/dev.c:6580\n   tun_get_user+0xa63/0x1120 drivers/net/tun.c:1909\n   tun_chr_write_iter+0x65/0xb0 drivers/net/tun.c:1984\n   vfs_write+0x300/0x420 fs/read_write.c:593\n   ksys_write+0x60/0xd0 fs/read_write.c:686\n   do_syscall_64+0x50/0x1c0 arch/x86/entry/syscall_64.c:63\n   </TASK>\n\nTo trigger gso segment in udp_queue_rcv_skb(), we should also set option\nUDP_ENCAP_ESPINUDP to enable udp_sk(sk)->encap_rcv. When the encap_rcv\nhook return 1 in udp_queue_rcv_one_skb(), udp_csum_pull_header() will try\nto pull udphdr, but the skb size has been segmented to gso size, which\nleads to this crash.\n\nPrevious commit cf329aa42b66 (\"udp: cope with UDP GRO packet misdirection\")\nintroduces segmentation in UDP receive path only for GRO, which was never\nintended to be used for UFO, so drop UFO packets in udp_rcv_segment().","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/0c639c6479ec4480372901a5fc566f7588cf5522","https://git.kernel.org/stable/c/0d45954034f8edd6d4052e0190d3d6335c37e4de","https://git.kernel.org/stable/c/4c1022220b1b6fea802175e80444923a3bbf93a5","https://git.kernel.org/stable/c/72f97d3cb791e26492236b2be7fd70d2c6222555","https://git.kernel.org/stable/c/791f32c5eab33ca3a153f8f6f763aa0df1ddc320"],"products":["debian:debian_linux","linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:07:46.309729541+00:00"},"epss":{"cve":"CVE-2025-38622","score":0.00183,"percentile":0.07901,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}