🛡️ CVE-2025-21692 on Debian — linux
Description
In the Linux kernel, the following vulnerability has been resolved: net: sched: fix ets qdisc OOB Indexing Haowei Yan <g1042620637@gmail.com> found that ets_class_from_arg() can index an Out-Of-Bound class in ets_class_from_arg() when passed clid of 0. The overflow may cause local privilege escalation. [ 18.852298] ------------[ cut here ]------------ [ 18.853271] UBSAN: array-index-out-of-bounds in net/sched/sch_ets.c:93:20 [ 18.853743] index 18446744073709551615 is out of range for type 'ets_class [16]' [ 18.854254] CPU: 0 UID: 0 PID: 1275 Comm: poc Not tainted 6.12.6-dirty #17 [ 18.854821] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 [ 18.856532] Call Trace: [ 18.857441] <TASK> [ 18.858227] dump_stack_lvl+0xc2/0xf0 [ 18.859607] dump_stack+0x10/0x20 [ 18.860908] __ubsan_handle_out_of_bounds+0xa7/0xf0 [ 18.864022] ets_class_change+0x3d6/0x3f0 [ 18.864322] tc_ctl_tclass+0x251/0x910 [ 18.864587] ? lock_acquire+0x5e/0x140 [ 18.865113] ? __mutex_lock+0x9c/0xe70 [ 18.866009] ? __mutex_lock+0xa34/0xe70 [ 18.866401] rtnetlink_rcv_msg+0x170/0x6f0 [ 18.866806] ? __lock_acquire+0x578/0xc10 [ 18.867184] ? __pfx_rtnetlink_rcv_msg+0x10/0x10 [ 18.867503] netlink_rcv_skb+0x59/0x110 [ 18.867776] rtnetlink_rcv+0x15/0x30 [ 18.868159] netlink_unicast+0x1c3/0x2b0 [ 18.868440] netlink_sendmsg+0x239/0x4b0 [ 18.868721] ____sys_sendmsg+0x3e2/0x410 [ 18.869012] ___sys_sendmsg+0x88/0xe0 [ 18.869276] ? rseq_ip_fixup+0x198/0x260 [ 18.869563] ? rseq_update_cpu_node_id+0x10a/0x190 [ 18.869900] ? trace_hardirqs_off+0x5a/0xd0 [ 18.870196] ? syscall_exit_to_user_mode+0xcc/0x220 [ 18.870547] ? do_syscall_64+0x93/0x150 [ 18.870821] ? __memcg_slab_free_hook+0x69/0x290 [ 18.871157] __sys_sendmsg+0x69/0xd0 [ 18.871416] __x64_sys_sendmsg+0x1d/0x30 [ 18.871699] x64_sys_call+0x9e2/0x2670 [ 18.871979] do_syscall_64+0x87/0x150 [ 18.873280] ? do_syscall_64+0x93/0x150 [ 18.874742] ? lock_release+0x7b/0x160 [ 18.876157] ? do_user_addr_fault+0x5ce/0x8f0 [ 18.877833] ? irqentry_exit_to_user_mode+0xc2/0x210 [ 18.879608] ? irqentry_exit+0x77/0xb0 [ 18.879808] ? clear_bhb_loop+0x15/0x70 [ 18.880023] ? clear_bhb_loop+0x15/0x70 [ 18.880223] ? clear_bhb_loop+0x15/0x70 [ 18.880426] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 18.880683] RIP: 0033:0x44a957 [ 18.880851] Code: ff ff e8 fc 00 00 00 66 2e 0f 1f 84 00 00 00 00 00 66 90 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 89 54 24 1c 48 8974 24 10 [ 18.881766] RSP: 002b:00007ffcdd00fad8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e [ 18.882149] RAX: ffffffffffffffda RBX: 00007ffcdd010db8 RCX: 000000000044a957 [ 18.882507] RDX: 0000000000000000 RSI: 00007ffcdd00fb70 RDI: 0000000000000003 [ 18.885037] RBP: 00007ffcdd010bc0 R08: 000000000703c770 R09: 000000000703c7c0 [ 18.887203] R10: 0000000000000080 R11: 0000000000000246 R12: 0000000000000001 [ 18.888026] R13: 00007ffcdd010da8 R14: 00000000004ca7d0 R15: 0000000000000001 [ 18.888395] </TASK> [ 18.888610] ---[ end trace ]---
Distribution advisory
This page covers CVE-2025-21692 as tracked by Debian, for the package linux. The fix is available in version 6.12.12-1; earlier versions remain affected.
How this vulnerability can be exploited
This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.
Affected software
DEBIAN-CVE-2025-21692 is recorded against 2 packages.
- linux (fixed in 6.12.12-1)
- linux-6.1 (fixed in 6.1.128-1~deb11u1)
Timeline and source
Published on 10 February 2025 and last revised on 4 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.
References
CVE-2025-21692 on other distributions
Each distribution ships its own build and its own fixed version. Pick the one you run:
Details
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| linux | — | 6.12.12-1 |
| linux-6.1 | — | 6.1.128-1~deb11u1 |
References
Similar Threats
- Unknown CGA-23jx-hhcx-m389
- Unknown CGA-2qp7-6757-fmgc
- Unknown CGA-2rj5-jc55-r267
- Unknown CGA-3m96-cwq8-6xmx
- Unknown CGA-3qj9-973w-fh9g
Site Security Check
Is linux part of your stack?
DEBIAN-CVE-2025-21692 is rated CVSS 7.8 High. BotEraser scans your installation against known CVE records and tells you whether this vulnerability applies to the versions you actually run.
Scan My Site Free →No credit card required · Results in minutes
ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.