Answer in brief
CVE-2025-21653 records a Unknown severity vulnerability in net_sched: cls_flow: validate TCA_FLOW_RSHIFT attribute. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 TM MFP - BIOS (generic), Siemens/SIMATIC S7-1500 TM MFP - GNU/Linux subsystem (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 TM MFP - BIOS (generic), Siemens/SIMATIC S7-1500 TM MFP - GNU/Linux subsystem (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=e5dfb815181fcb186d6080ac3a091eadff2d98fe <9858f4afeb2e59506e714176bd3e135539a3eeec || >=e5dfb815181fcb186d6080ac3a091eadff2d98fe <43658e4a5f2770ad94e93362885ff51c10cf3179 || >=e5dfb815181fcb186d6080ac3a091eadff2d98fe <a313d6e6d5f3a631cae5a241c392c28868aa5c5e || >=e5dfb815181fcb186d6080ac3a091eadff2d98fe <2011749ca96460386844dfc7e0fde53ebee96f3c || >=e5dfb815181fcb186d6080ac3a091eadff2d98fe <e54beb9aed2a90dddf4c5d68fcfc9a01f3e40a61 || >=e5dfb815181fcb186d6080ac3a091eadff2d98fe <6fde663f7321418996645ee602a473457640542f || >=e5dfb815181fcb186d6080ac3a091eadff2d98fe <a039e54397c6a75b713b9ce7894a62e06956aa92 | 9858f4afeb2e59506e714176bd3e135539a3eeec, 43658e4a5f2770ad94e93362885ff51c10cf3179, a313d6e6d5f3a631cae5a241c392c28868aa5c5e, 2011749ca96460386844dfc7e0fde53ebee96f3c, e54beb9aed2a90dddf4c5d68fcfc9a01f3e40a61, 6fde663f7321418996645ee602a473457640542f, a039e54397c6a75b713b9ce7894a62e06956aa92 |
| Linux/Linuxgeneric | 2.6.25 | Not reported |
| Siemens/SIMATIC S7-1500 TM MFP - BIOSgeneric | >=0 <* | * |
| Siemens/SIMATIC S7-1500 TM MFP - GNU/Linux subsystemgeneric | >=0 <* | * |
Published upstream
Jan 19, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 15, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 15, 2026
In the Linux kernel, the following vulnerability has been resolved: net_sched: cls_flow: validate TCA_FLOW_RSHIFT attribute syzbot found that TCA_FLOW_RSHIFT attribute was not validated. Right shitfing a 32bit integer is undefined for large shift values. UBSAN: shift-out-of-bounds in net/sched/cls_flow.c:329:23 shift exponent 9445 is too large for 32-bit type 'u32' (aka 'unsigned int') CPU: 1 UID: 0 PID: 54 Comm: kworker/u8:3 Not tainted 6.13.0-rc3-syzkaller-00180-g4f619d518db9 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: ipv6_addrconf addrconf_dad_work Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 ubsan_epilogue lib/ubsan.c:231 [inline] __ubsan_handle_shift_out_of_bounds+0x3c8/0x420 lib/ubsan.c:468 flow_classify+0x24d5/0x25b0 net/sched/cls_flow.c:329 tc_classify include/net/tc_wrapper.h:197 [inline] __tcf_classify net/sched/cls_api.c:1771 [inline] tcf_classify+0x420/0x1160 net/sched/cls_api.c:1867 sfb_classify net/sched/sch_sfb.c:260 [inline] sfb_enqueue+0x3ad/0x18b0 net/sched/sch_sfb.c:318 dev_qdisc_enqueue+0x4b/0x290 net/core/dev.c:3793 __dev_xmit_skb net/core/dev.c:3889 [inline] __dev_queue_xmit+0xf0e/0x3f50 net/core/dev.c:4400 dev_queue_xmit include/linux/netdevice.h:3168 [inline] neigh_hh_output include/net/neighbour.h:523 [inline] neigh_output include/net/neighbour.h:537 [inline] ip_finish_output2+0xd41/0x1390 net/ipv4/ip_output.c:236 iptunnel_xmit+0x55d/0x9b0 net/ipv4/ip_tunnel_core.c:82 udp_tunnel_xmit_skb+0x262/0x3b0 net/ipv4/udp_tunnel_core.c:173 geneve_xmit_skb drivers/net/geneve.c:916 [inline] geneve_xmit+0x21dc/0x2d00 drivers/net/geneve.c:1039 __netdev_start_xmit include/linux/netdevice.h:5002 [inline] netdev_start_xmit include/linux/netdevice.h:5011 [inline] xmit_one net/core/dev.c:3590 [inline] dev_hard_start_xmit+0x27a/0x7d0 net/core/dev.c:3606 __dev_queue_xmit+0x1b73/0x3f50 net/core/dev.c:4434
Quoted source text, attributed separately from HOL analysis.