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VulnerabilityAwaiting classification

CVE-2025-68263

CRITICAL · 9.8 CVSS v3.1 Published 2025-12-16
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: ksmbd: ipc: fix use-after-free in ipc_msg_send_request ipc_msg_send_request() waits for a generic netlink reply using an ipc_msg_table_entry on the stack. The generic netlink handler (handle_generic_event()/handle_response()) fills entry->response under ipc_msg_table_lock, but ipc_msg_send_request() used to validate and free entry->response without holding the same lock. Under high concurrency this allows a race where handle_response() is copying data into entry->response while ipc_msg_send_request() has just freed it, leading to a slab-use-after-free reported by KASAN in handle_generic_event(): BUG: KASAN: slab-use-after-free in handle_generic_event+0x3c4/0x5f0 [ksmbd] Write of size 12 at addr ffff888198ee6e20 by task pool/109349 ... Freed by task: kvfree ipc_msg_send_request [ksmbd] ksmbd_rpc_open -> ksmbd_session_rpc_open [ksmbd] Fix by: - Taking ipc_msg_table_lock in ipc_msg_send_request() while validating entry->response, freeing it when invalid, and removing the entry from ipc_msg_table. - Returning the final entry->response pointer to the caller only after the hash entry is removed under the lock. - Returning NULL in the error path, preserving the original API semantics. This makes all accesses to entry->response consistent with handle_response(), which already updates and fills the response buffer under ipc_msg_table_lock, and closes the race that allowed the UAF.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Use-after-free vulnerability in Linux kernel ksmbd module's IPC message handling. The ipc_msg_send_request() function validates and frees entry->response without holding ipc_msg_table_lock while handle_response() writes to the same buffer under the lock, creating a race condition under high concurrency that leads to slab-use-after-free.

MitigationApply the kernel patch that ensures ipc_msg_table_lock is held while validating and freeing entry->response and removing the entry from ipc_msg_table, consistent with how handle_response() accesses the buffer.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify ksmbd module is loaded
    Run 'lsmod | grep ksmbd' or check 'ls /sys/module/ | grep ksmbd' to see if the ksmbd kernel module is present
    Affected if ksmbd module is loaded or compiled into the kernel - the vulnerability only applies when ksmbd is active
  2. Check kernel version
    Run 'uname -r' to obtain the running kernel version and compare it to the version range containing the fix for this race condition
    Affected if kernel version is older than the patched version that addresses the ipc_msg_send_request use-after-free in ksmbd
  3. Confirm ksmbd daemon is running
    Check if the ksmbd daemon process is active: run 'ps aux | grep ksmbd' or check for 'ksmbd' in /proc/*/comm, or verify the ksmbd mount is present via 'mount | grep ksmbd'
    Affected if ksmbd daemon or service is actively running - the race condition requires active IPC message handling between threads

User is affected if ksmbd module is loaded AND the kernel version is older than the patched version that serializes ipc_msg_table_lock during response validation and freeing in ipc_msg_send_request().

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the kernel patch that ensures ipc_msg_table_lock is held while validating and freeing entry->response and removing the entry from ipc_msg_table, consistent with how handle_response() accesses the buffer.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing16.0 h
  • Review / QA4.0 h
32.0 hours of engineering $5,360
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-68263 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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