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CVE-2025-21963 is an integer-overflow vulnerability in the Linux kernel CIFS client's processing of the acdirmax mount option. This user-provided unsigned 32-bit parameter specifies a duration in seconds and is intended to have an upper limit. The vulnerable implementation converts the value from seconds to jiffies before validating that limit, allowing the conversion to overflow and undermining the intended bounds check. The vulnerability was discovered by the Linux Verification Center using SVACE.
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An integer overflow vulnerability in the Linux kernel CIFS implementation occurs when the acdirmax mount parameter is converted from seconds to jiffies before validation. The advisory rates it medium severity, with a CVSS v3 score of 5.5 indicating local access, low privileges, and high availability impact. The recommended fix is to update sys-kernel/csql-kernel-6_1 and related packages to version 18613.164.121 or later.
A Linux kernel CIFS vulnerability caused by an integer overflow while processing the acdirmax mount option.
An integer overflow in the Linux kernel CIFS implementation occurs when the acdirmax mount option is converted from seconds to jiffies before validation. The advisory assigns CVSS v3 severity 5.5, indicating a local, low-privilege vulnerability with high availability impact and no confidentiality or integrity impact.
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