In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix recursive locking in RPC handle list access
Since commit 305853cce3794 ("ksmbd: Fix race condition in RPC handle list
access"), ksmbd_session_rpc_method() attempts to lock sess->rpc_lock.
This causes hung connections / tasks when a client attempts to open
a named pipe. Using Samba's rpcclient tool:
$ rpcclient //192.168.1.254 -U user%password
$ rpcclient $> srvinfo
Kernel side:
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:0 state:D stack:0 pid:5021 tgid:5021 ppid:2 flags:0x00200000
Workqueue: ksmbd-io handle_ksmbd_work
Call trace:
__schedule from schedule+0x3c/0x58
schedule from schedule_preempt_disabled+0xc/0x10
schedule_preempt_disabled from rwsem_down_read_slowpath+0x1b0/0x1d8
rwsem_down_read_slowpath from down_read+0x28/0x30
down_read from ksmbd_session_rpc_method+0x18/0x3c
ksmbd_session_rpc_method from ksmbd_rpc_open+0x34/0x68
ksmbd_rpc_open from ksmbd_session_rpc_open+0x194/0x228
ksmbd_session_rpc_open from create_smb2_pipe+0x8c/0x2c8
create_smb2_pipe from smb2_open+0x10c/0x27ac
smb2_open from handle_ksmbd_work+0x238/0x3dc
handle_ksmbd_work from process_scheduled_works+0x160/0x25c
process_scheduled_works from worker_thread+0x16c/0x1e8
worker_thread from kthread+0xa8/0xb8
kthread from ret_from_fork+0x14/0x38
Exception stack(0x8529ffb0 to 0x8529fff8)
The task deadlocks because the lock is already held:
ksmbd_session_rpc_open
down_write(&sess->rpc_lock)
ksmbd_rpc_open
ksmbd_session_rpc_method
down_read(&sess->rpc_lock) <-- deadlock
Adjust ksmbd_session_rpc_method() callers to take the lock when necessary.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (5.5): severity, escalated by confirmed exploitation. This CVE's 5.5 is its impact severity (EG Severity), not escalated.
- EG Severity
- 5.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). 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 fixed version is listed under Patch Availability. 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