CVE-2023-6610 Overview
CVE-2023-6610 is an out-of-bounds read vulnerability in the smb2_dump_detail function located in fs/smb/client/smb2ops.c within the Linux Kernel SMB2 client implementation. A local attacker with low privileges can trigger the flaw to crash the system or leak internal kernel memory contents. The vulnerability affects upstream Linux Kernel builds and Red Hat Enterprise Linux 8 and 9. Red Hat has issued multiple security advisories addressing the issue across affected kernel packages. The flaw is tracked under [CWE-125: Out-of-bounds Read].
Critical Impact
A local, authenticated attacker can crash the kernel or disclose sensitive kernel memory, undermining system confidentiality and availability on affected Linux hosts.
Affected Products
- Linux Kernel (upstream, SMB client subsystem)
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
Discovery Timeline
- 2023-12-08 - CVE-2023-6610 published to NVD
- 2024-11-21 - Last updated in NVD database
Technical Details for CVE-2023-6610
Vulnerability Analysis
The vulnerability resides in the smb2_dump_detail routine of the Linux Kernel's SMB2 client code at fs/smb/client/smb2ops.c. This function is used to print details about Server Message Block version 2 (SMB2) protocol structures, typically for debugging and tracing. During this dump operation, the kernel reads protocol fields without sufficient bounds validation against the actual size of the buffer holding the SMB2 response. A local attacker who can interact with the SMB client subsystem can drive it into a state where smb2_dump_detail reads past the end of the allocated structure. The read either references unmapped memory and panics the kernel, or returns adjacent kernel data that can be observed by the attacker.
Root Cause
The root cause is missing or insufficient length validation in smb2_dump_detail before dereferencing fields of an SMB2 protocol header. The function assumes the buffer contains a fully populated SMB2 structure, but malformed or truncated responses processed by the client can shorten the actual payload. Reading offsets beyond the buffer boundary produces the out-of-bounds access classified as [CWE-125].
Attack Vector
Exploitation requires local access with at least low privileges on the target host. An attacker triggers SMB2 client code paths that invoke debug dumping of protocol details, for example by mounting or interacting with a malicious or attacker-controlled SMB server, then induces processing of a malformed response. No user interaction is required beyond the attacker's own actions. Successful exploitation yields denial of service via kernel crash, or partial disclosure of kernel memory contents that may aid in further privilege escalation chains.
No public proof-of-concept exploit has been published, and the issue is not listed in the CISA Known Exploited Vulnerabilities catalog. See the Kernel Bug Report #218219 and Red Hat CVE Analysis for CVE-2023-6610 for upstream technical context.
Detection Methods for CVE-2023-6610
Indicators of Compromise
- Unexpected kernel oops or panic entries in dmesg or /var/log/messages referencing smb2_dump_detail, smb2ops, or cifs modules.
- Repeated client-side SMB2 mount attempts to untrusted or unusual remote endpoints from non-administrative users.
- KASAN or slab corruption warnings tied to the cifs kernel module when SMB2 debugging is enabled.
Detection Strategies
- Audit loaded kernel modules and confirm whether cifs is loaded on systems that do not require SMB client functionality.
- Inventory hosts running affected kernel builds by correlating uname -r output with Red Hat advisories such as RHSA-2024:0723 and RHSA-2024:0881.
- Use vulnerability scanners and configuration management tools to flag kernels predating the fixed RHEL package versions.
Monitoring Recommendations
- Forward kernel logs to a centralized logging or SIEM platform and alert on SMB-related oops, KASAN, or general protection fault events.
- Monitor for outbound SMB connections from unexpected user contexts or service accounts.
- Track host availability metrics for unexplained reboots that may indicate kernel crashes triggered by the flaw.
How to Mitigate CVE-2023-6610
Immediate Actions Required
- Apply the kernel updates referenced in the Red Hat advisories below to all affected RHEL 8 and RHEL 9 systems.
- For upstream Linux deployments, update to a kernel release that includes the fix in fs/smb/client/smb2ops.c.
- Restrict local shell and SMB client usage on multi-user systems until patches are deployed.
Patch Information
Red Hat addressed CVE-2023-6610 through a series of kernel errata, including RHSA-2024:0723, RHSA-2024:0724, RHSA-2024:0725, RHSA-2024:0881, RHSA-2024:0897, RHSA-2024:1248, RHSA-2024:1404, and RHSA-2024:2094. Additional engineering context is available in Red Hat Bug Report #2253614.
Workarounds
- Blacklist the cifs kernel module on systems that do not require SMB client functionality to prevent the vulnerable code path from loading.
- Disable kernel SMB2 debug tracing where it is enabled, reducing exposure of smb2_dump_detail invocations.
- Limit which local users can mount SMB shares by tightening sudo rules and removing the SUID bit from helper binaries such as mount.cifs where operationally feasible.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
