{"cve":"CVE-2025-21653","nvd":{"published":"2025-01-19T11:15:10.940","modified":"2026-06-17T08:43:56.533","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet_sched: cls_flow: validate TCA_FLOW_RSHIFT attribute\n\nsyzbot found that TCA_FLOW_RSHIFT attribute was not validated.\nRight shitfing a 32bit integer is undefined for large shift values.\n\nUBSAN: shift-out-of-bounds in net/sched/cls_flow.c:329:23\nshift exponent 9445 is too large for 32-bit type 'u32' (aka 'unsigned int')\nCPU: 1 UID: 0 PID: 54 Comm: kworker/u8:3 Not tainted 6.13.0-rc3-syzkaller-00180-g4f619d518db9 #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024\nWorkqueue: ipv6_addrconf addrconf_dad_work\nCall Trace:\n <TASK>\n  __dump_stack lib/dump_stack.c:94 [inline]\n  dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120\n  ubsan_epilogue lib/ubsan.c:231 [inline]\n  __ubsan_handle_shift_out_of_bounds+0x3c8/0x420 lib/ubsan.c:468\n  flow_classify+0x24d5/0x25b0 net/sched/cls_flow.c:329\n  tc_classify include/net/tc_wrapper.h:197 [inline]\n  __tcf_classify net/sched/cls_api.c:1771 [inline]\n  tcf_classify+0x420/0x1160 net/sched/cls_api.c:1867\n  sfb_classify net/sched/sch_sfb.c:260 [inline]\n  sfb_enqueue+0x3ad/0x18b0 net/sched/sch_sfb.c:318\n  dev_qdisc_enqueue+0x4b/0x290 net/core/dev.c:3793\n  __dev_xmit_skb net/core/dev.c:3889 [inline]\n  __dev_queue_xmit+0xf0e/0x3f50 net/core/dev.c:4400\n  dev_queue_xmit include/linux/netdevice.h:3168 [inline]\n  neigh_hh_output include/net/neighbour.h:523 [inline]\n  neigh_output include/net/neighbour.h:537 [inline]\n  ip_finish_output2+0xd41/0x1390 net/ipv4/ip_output.c:236\n  iptunnel_xmit+0x55d/0x9b0 net/ipv4/ip_tunnel_core.c:82\n  udp_tunnel_xmit_skb+0x262/0x3b0 net/ipv4/udp_tunnel_core.c:173\n  geneve_xmit_skb drivers/net/geneve.c:916 [inline]\n  geneve_xmit+0x21dc/0x2d00 drivers/net/geneve.c:1039\n  __netdev_start_xmit include/linux/netdevice.h:5002 [inline]\n  netdev_start_xmit include/linux/netdevice.h:5011 [inline]\n  xmit_one net/core/dev.c:3590 [inline]\n  dev_hard_start_xmit+0x27a/0x7d0 net/core/dev.c:3606\n  __dev_queue_xmit+0x1b73/0x3f50 net/core/dev.c:4434","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/2011749ca96460386844dfc7e0fde53ebee96f3c","https://git.kernel.org/stable/c/43658e4a5f2770ad94e93362885ff51c10cf3179","https://git.kernel.org/stable/c/6fde663f7321418996645ee602a473457640542f","https://git.kernel.org/stable/c/9858f4afeb2e59506e714176bd3e135539a3eeec","https://git.kernel.org/stable/c/a039e54397c6a75b713b9ce7894a62e06956aa92"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:58:41.599736885+00:00"},"epss":{"cve":"CVE-2025-21653","score":0.00214,"percentile":0.1178,"date":"2026-10-31"},"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."]}