CVE-2025-40281: Linux

EPSS: 0.2% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: sctp: prevent possible shift-out-of-bounds in sctp_transport_update_rto syzbot reported a possible shift-out-of-bounds [1] Blamed commit added rto_alpha_max and rto_beta_max set to 1000. It is unclear if some sctp users are setting very large rto_alpha and/or rto_beta. In order to prevent user regression, perform the test at run time. Also add READ_ONCE() annotations as sysctl values can change under us. [1] UBSAN: shift-out-of-bounds in net/sctp/transport.c:509:41 shift exponent 64 is too large for 32-bit type 'unsigned int' CPU: 0 UID: 0 PID: 16704 Comm: syz.2.2320 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x16c/0x1f0 lib/dump_stack.c:120 ubsan_epilogue lib/ubsan.c:233 [inline] __ubsan_handle_shift_out_of_bounds+0x27f/0x420 lib/ubsan.c:494 sctp_transport_update_rto.cold+0x1c/0x34b net/sctp/transport.c:509 sctp_check_transmitted+0x11c4/0x1c30 net/sctp/outqueue.c:1502 sctp_outq_sack+0x4ef/0x1b20 net/sctp/outqueue.c:1338 sctp_cmd_process_sack net/sctp/sm_sideeffect.c:840 [inline] sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1372 [inline]

Affected products

• Linux Linux: from 3.16, before 5.4.302 (fixed in 5.4.302); from 5.5, before 5.10.247 (fixed in 5.10.247); from 5.11, before 5.15.197 (fixed in 5.15.197); from 5.16, before 6.1.159 (fixed in 6.1.159); from 6.2, before 6.6.117 (fixed in 6.6.117); from 6.7, before 6.12.59 (fixed in 6.12.59); …
• Siemens Ruggedcom RST2428P: before V4.0 (fixed in V4.0)

Published 2025-12-06. Last modified 2026-06-17.