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CVE-2025-22043
ksmbd: add bounds check for durable handle context
Published 2025-04-16 (18 months ago) by the Linux kernel CNA. Subsystem fs/smb. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2025-22043 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | fixed | 6.12.25-1 | Update the kernel and reboot. Fixed in 6.12.25-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 6.12.25-1 | Update the kernel and reboot. Fixed in 6.12.25-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 6.12.25-1 | Update the kernel and reboot. Fixed in 6.12.25-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Add missing bounds check for durable handle context.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
fs/smb/server/smb2pdu.c
- What this is
- KERNEL SMB3 SERVER (KSMBD)MAINTAINERS section matched on fs/smb/server/ · linux-cifs@vger.kernel.org · Maintained
- Kernel module
- ksmbd
Check it on the machine
grep -wE 'CONFIG_SMBFS|CONFIG_SMB_SERVER' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w ksmbdPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this as a loadable module. Every release below compiles it as a module on every flavour, so whether the code is in the running kernel depends on whether that module is loaded.
- bookworm, trixie, forky, sidm
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- Build switches
- CONFIG_SMBFS, CONFIG_SMB_SERVER
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2025-04-16 (18 months ago)source
- CVSS
- 8.1 high
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.49%, higher than 40.4% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- fs/smb
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.15 | 6.6.87 | 8d4848c45943 |
| 5.15 | 6.12.23 | 29b946714d6a |
| 5.15 | 6.13.11 | 1107b9ed9219 |
| 5.15 | 6.14.2 | f0db3d9d416e |
| 5.15 | 6.15 | 542027e123fc |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:NAttack vector, network
- ksmbd is the in-kernel SMB server listening on TCP/445; the malformed SMB2 CREATE request with a crafted durable-handle create context is delivered entirely over the network by a remote peer.
- AC:LAttack complexity, low
- The attacker fully controls the create-context DataOffset/DataLength and struct layout in the request; the undersized context reliably triggers the out-of-bounds read with no uncontrolled preconditions.
- PR:LPrivileges required, low
- SMB2_CREATE is only dispatched after a valid authenticated session (smb2_check_user_session) and tree connect exist, so the attacker needs valid (even low-privilege/guest) SMB credentials — this is post-authentication, not a handshake path.
- UI:NUser interaction, none
- The attacker triggers the flaw purely by sending a crafted create request; no action by any local user or victim is required.
- S:UScope, unchanged
- The out-of-bounds read stays within the kernel's own memory and security authority; no boundary such as a VM/hypervisor or IOMMU is crossed.
- C:HConfidentiality impact, high
- The bug reads tens of bytes of adjacent kernel heap memory beyond the request buffer (well past "a few bytes"), which per kernel OOB-read guidance is High confidentiality impact.
- I:NIntegrity impact, none
- The defect is strictly a read; it provides no memory-write or corruption primitive, and the OOB-sourced file id/GUID values cannot be steered to a controlled durable-handle takeover.
- A:HAvailability impact, high
- The out-of-bounds read can dereference an unmapped/guard page (kvmalloc/vmalloc-backed buffers) or trip KASAN, producing a kernel oops/panic and denial of service.