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
==================================================================
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (7.8): severity, escalated by confirmed exploitation. This CVE's 7.8 is its impact severity (EG Severity), not escalated.
- EG Severity
- 7.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-26). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it