# CVE-2025-38666: net: appletalk: Fix use-after-free in AARP proxy probe CVE-2025-38666 is fixed in 9 products on 1 platform, first by DEBIAN-CVE-2025-38666, released August 22, 2025. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2025-38666 - Priority: High - CVSS: 7.8 (high) - EPSS: 0.0017 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Aug 22, 2025 - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-38666 ## Description In the Linux kernel, the following vulnerability has been resolved: net: appletalk: Fix use-after-free in AARP proxy probe The AARP proxy‐probe routine (aarp_proxy_probe_network) sends a probe, releases the aarp_lock, sleeps, then re-acquires the lock. During that window an expire timer thread (__aarp_expire_timer) can remove and kfree() the same entry, leading to a use-after-free. race condition: cpu 0 | cpu 1 atalk_sendmsg() | atif_proxy_probe_device() aarp_send_ddp() | aarp_proxy_probe_network() mod_timer() | lock(aarp_lock) // LOCK!! timeout around 200ms | alloc(aarp_entry) and then call | proxies[hash] = aarp_entry aarp_expire_timeout() | aarp_send_probe() | unlock(aarp_lock) // UNLOCK!! lock(aarp_lock) // LOCK!! | msleep(100); __aarp_expire_timer(&proxies[ct]) | free(aarp_entry) | unlock(aarp_lock) // UNLOCK!! | | lock(aarp_lock) // LOCK!! | UAF aarp_entry !! ================================================================== BUG: KASAN: slab-use-after-free in aarp_proxy_probe_network+0x560/0x630 net/appletalk/aarp.c:493 Read of size 4 at addr ffff8880123aa360 by task repro/13278 CPU: 3 UID: 0 PID: 13278 Comm: repro Not tainted 6.15.2 #3 PREEMPT(full) Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1b0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:408 [inline] print_report+0xc1/0x630 mm/kasan/report.c:521 kasan_report+0xca/0x100 mm/kasan/report.c:634 aarp_proxy_probe_network+0x560/0x630 net/appletalk/aarp.c:493 atif_proxy_probe_device net/appletalk/ddp.c:332 [inline] atif_ioctl+0xb58/0x16c0 net/appletalk/ddp.c:857 atalk_ioctl+0x198/0x2f0 net/appletalk/ddp.c:1818 sock_do_ioctl+0xdc/0x260 net/socket.c:1190 sock_ioctl+0x239/0x6a0 net/socket.c:1311 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl fs/ioctl.c:892 [inline] __x64_sys_ioctl+0x194/0x200 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcb/0x250 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Allocated: aarp_alloc net/appletalk/aarp.c:382 [inline] aarp_proxy_probe_network+0xd8/0x630 net/appletalk/aarp.c:468 atif_proxy_probe_device net/appletalk/ddp.c:332 [inline] atif_ioctl+0xb58/0x16c0 net/appletalk/ddp.c:857 atalk_ioctl+0x198/0x2f0 net/appletalk/ddp.c:1818 Freed: kfree+0x148/0x4d0 mm/slub.c:4841 __aarp_expire net/appletalk/aarp.c:90 [inline] __aarp_expire_timer net/appletalk/aarp.c:261 [inline] aarp_expire_timeout+0x480/0x6e0 net/appletalk/aarp.c:317 The buggy address belongs to the object at ffff8880123aa300 which belongs to the cache kmalloc-192 of size 192 The buggy address is located 96 bytes inside of freed 192-byte region [ffff8880123aa300, ffff8880123aa3c0) Memory state around the buggy address: ffff8880123aa200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8880123aa280: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc >ffff8880123aa300: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880123aa380: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff8880123aa400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ================================================================== ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | kernel-uek ol 8 | 0:5.4.17-2136.348.3.el7uek | [ELSA-2025-20663](https://patchblox.com/security/data/fix/linux/elsa-2025-20663.md) | Oct 11, 2025 | | Linux | kernel-uek-container ol 8 | 0:5.4.17-2136.348.3.el7uek | [ELSA-2025-20663](https://patchblox.com/security/data/fix/linux/elsa-2025-20663.md) | Oct 11, 2025 | | Linux | kernel-uek-container-debug ol 8 | 0:5.4.17-2136.348.3.el7uek | [ELSA-2025-20663](https://patchblox.com/security/data/fix/linux/elsa-2025-20663.md) | Oct 11, 2025 | | Linux | kernel-uek-debug ol 8 | 0:5.4.17-2136.348.3.el7uek | [ELSA-2025-20663](https://patchblox.com/security/data/fix/linux/elsa-2025-20663.md) | Oct 11, 2025 | | Linux | kernel-uek-debug-devel ol 8 | 0:5.4.17-2136.348.3.el7uek | [ELSA-2025-20663](https://patchblox.com/security/data/fix/linux/elsa-2025-20663.md) | Oct 11, 2025 | | Linux | kernel-uek-devel ol 8 | 0:5.4.17-2136.348.3.el7uek | [ELSA-2025-20663](https://patchblox.com/security/data/fix/linux/elsa-2025-20663.md) | Oct 11, 2025 | | Linux | kernel-uek-doc ol 8 | 0:5.4.17-2136.348.3.el7uek | [ELSA-2025-20663](https://patchblox.com/security/data/fix/linux/elsa-2025-20663.md) | Oct 11, 2025 | | Linux | kernel-uek-tools ol 8 | 0:5.4.17-2136.348.3.el7uek | [ELSA-2025-20663](https://patchblox.com/security/data/fix/linux/elsa-2025-20663.md) | Oct 11, 2025 | | Linux | linux Debian 12.15 (bookworm) | 6.1.148-1 | [DEBIAN-CVE-2025-38666](https://patchblox.com/security/data/fix/linux/debian-cve-2025-38666.md) | Aug 22, 2025 | | Linux | linux Debian 13.5 (trixie) | 6.12.41-1 | [DEBIAN-CVE-2025-38666](https://patchblox.com/security/data/fix/linux/debian-cve-2025-38666.md) | Aug 22, 2025 | | Linux | linux Debian 14 | 6.16.3-1 | [DEBIAN-CVE-2025-38666](https://patchblox.com/security/data/fix/linux/debian-cve-2025-38666.md) | Aug 22, 2025 | --- Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.