CVE-2026-23095
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: gue: Fix skb memleak with inner IP protocol 0. syzbot reported skb memleak below. [0] The repro generated a GUE packet with its inner protocol 0. gue_udp_recv() returns -guehdr->proto_ctype for "resubmit" in ip_protocol_deliver_rcu(), but this only works with non-zero protocol number. Let's drop such packets. Note that 0 is a valid number (IPv6 Hop-by-Hop Option). I think it is not practical to encap HOPOPT in GUE, so once someone starts to complain, we could pass down a resubmit flag pointer to distinguish two zeros from the upper layer: * no error * resubmit HOPOPT [0] BUG: memory leak unreferenced object 0xffff888109695a00 (size 240): comm "syz.0.17", pid 6088, jiffies 4294943096 hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 40 c2 10 81 88 ff ff 00 00 00 00 00 00 00 00 .@.............. backtrace (crc a84b336f): kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline] slab_post_alloc_hook mm/slub.c:4958 [inline] slab_alloc_node mm/slub.c:5263 [inline] kmem_cache_alloc_noprof+0x3b4/0x590 mm/slub.c:5270 __build_skb+0x23/0x60 net/core/skbuff.c:474 build_skb+0x20/0x190 net/core/skbuff.c:490 __tun_build_skb drivers/net/tun.c:1541 [inline] tun_build_skb+0x4a1/0xa40 drivers/net/tun.c:1636 tun_get_user+0xc12/0x2030 drivers/net/tun.c:1770 tun_chr_write_iter+0x71/0x120 drivers/net/tun.c:1999 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x45d/0x710 fs/read_write.c:686 ksys_write+0xa7/0x170 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xa4/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f
Severity
MEDIUM
CVSS score
5.5
(v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-02-04 17:16:20.370000
Last modified
2026-10-19 19:17:35.827000
View original CVE JSON
{
"id": "CVE-2026-23095",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-02-04T17:16:20.370",
"lastModified": "2026-10-19T19:17:35.827",
"vulnStatus": "Modified",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ngue: Fix skb memleak with inner IP protocol 0.\n\nsyzbot reported skb memleak below. [0]\n\nThe repro generated a GUE packet with its inner protocol 0.\n\ngue_udp_recv() returns -guehdr->proto_ctype for \"resubmit\"\nin ip_protocol_deliver_rcu(), but this only works with\nnon-zero protocol number.\n\nLet's drop such packets.\n\nNote that 0 is a valid number (IPv6 Hop-by-Hop Option).\n\nI think it is not practical to encap HOPOPT in GUE, so once\nsomeone starts to complain, we could pass down a resubmit\nflag pointer to distinguish two zeros from the upper layer:\n\n * no error\n * resubmit HOPOPT\n\n[0]\nBUG: memory leak\nunreferenced object 0xffff888109695a00 (size 240):\n comm \"syz.0.17\", pid 6088, jiffies 4294943096\n hex dump (first 32 bytes):\n 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................\n 00 40 c2 10 81 88 ff ff 00 00 00 00 00 00 00 00 .@..............\n backtrace (crc a84b336f):\n kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]\n slab_post_alloc_hook mm/slub.c:4958 [inline]\n slab_alloc_node mm/slub.c:5263 [inline]\n kmem_cache_alloc_noprof+0x3b4/0x590 mm/slub.c:5270\n __build_skb+0x23/0x60 net/core/skbuff.c:474\n build_skb+0x20/0x190 net/core/skbuff.c:490\n __tun_build_skb drivers/net/tun.c:1541 [inline]\n tun_build_skb+0x4a1/0xa40 drivers/net/tun.c:1636\n tun_get_user+0xc12/0x2030 drivers/net/tun.c:1770\n tun_chr_write_iter+0x71/0x120 drivers/net/tun.c:1999\n new_sync_write fs/read_write.c:593 [inline]\n vfs_write+0x45d/0x710 fs/read_write.c:686\n ksys_write+0xa7/0x170 fs/read_write.c:738\n do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0xa4/0xf80 arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x77/0x7f"
},
{
"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\ngue: Corrige la fuga de memoria de skb con el protocolo IP interno 0.\n\nsyzbot informó de una fuga de memoria de skb a continuación. [0]\n\nLa reproducción generó un paquete GUE con su protocolo interno 0.\n\ngue_udp_recv() devuelve -guehdr->proto_ctype para 'resubmit' en ip_protocol_deliver_rcu(), pero esto solo funciona con números de protocolo distintos de cero.\n\nDescartemos tales paquetes.\n\nTenga en cuenta que 0 es un número válido (Opción Salto a Salto de IPv6).\n\nCreo que no es práctico encapsular HOPOPT en GUE, así que una vez que alguien empiece a quejarse, podríamos pasar un puntero de bandera de reenvío para distinguir dos ceros de la capa superior:\n\n * sin error\n * reenviar HOPOPT\n\n[0]\nBUG: fuga de memoria\nobjeto sin referencia 0xffff888109695a00 (tamaño 240):\n comm 'syz.0.17', pid 6088, jiffies 4294943096\n volcado hexadecimal (primeros 32 bytes):\n 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................\n 00 40 c2 10 81 88 ff ff 00 00 00 00 00 00 00 00 .@..............\n rastreo (crc a84b336f):\n kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]\n slab_post_alloc_hook mm/slub.c:4958 [inline]\n slab_alloc_node mm/slub.c:5263 [inline]\n kmem_cache_alloc_noprof+0x3b4/0x590 mm/slub.c:5270\n __build_skb+0x23/0x60 net/core/skbuff.c:474\n build_skb+0x20/0x190 net/core/skbuff.c:490\n __tun_build_skb drivers/net/tun.c:1541 [inline]\n tun_build_skb+0x4a1/0xa40 drivers/net/tun.c:1636\n tun_get_user+0xc12/0x2030 drivers/net/tun.c:1770\n tun_chr_write_iter+0x71/0x120 drivers/net/tun.c:1999\n new_sync_write fs/read_write.c:593 [inline]\n vfs_write+0x45d/0x710 fs/read_write.c:686\n ksys_write+0xa7/0x170 fs/read_write.c:738\n do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0xa4/0xf80 arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x77/0x7f"
}
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