CVE-2026-72103

In the Linux kernel, the following vulnerability has been resolved:

dm: avoid leaking the callers thread keyring via the table device file

The refactoring in commit a28d893eb327 (md: port block device access to file) accidentally causes the callers thread keyring to be kept alive long beyond the callers lifetime.

As a result, cryptsetup luksSuspend silently fails to wipe the LUKS volume key from memory.

In detail: cryptsetup luksOpen uses its supposedly ephemeral thread keyring to pass the volume key to the kernel. dm-crypts crypt_set_keyring_key() copies the key material into its own crypt_config structure and then drops its own reference to the key in the keyring with key_put().

With this fix, restoring pre-v6.9 behavior, the copy in the thread keyring is then promptly garbage collected, such that exactly one copy of the volume key remains. This single copy is correctly wiped from memory on cryptsetup luksSuspend.

Without this fix, the thread keyring and the volume key in it remains. This second copy is only freed on luksClose. luksSuspend neither knows about this copy nor has any way to remove it, so the key remains recoverable from RAM after a suspend that is documented to have wiped it.

This fix should not introduce new security problems, as the code is anyway gated by CAP_SYS_ADMIN. The device-mapper core, not the calling task, is the legitimate owner of this long-lived file.

Weakness

The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.

Affected Software

Extended Description

There are many different kinds of mistakes that introduce information exposures. The severity of the error can range widely, depending on the context in which the product operates, the type of sensitive information that is revealed, and the benefits it may provide to an attacker. Some kinds of sensitive information include:

Information might be sensitive to different parties, each of which may have their own expectations for whether the information should be protected. These parties include:

Information exposures can occur in different ways:

It is common practice to describe any loss of confidentiality as an “information exposure,” but this can lead to overuse of CWE-200 in CWE mapping. From the CWE perspective, loss of confidentiality is a technical impact that can arise from dozens of different weaknesses, such as insecure file permissions or out-of-bounds read. CWE-200 and its lower-level descendants are intended to cover the mistakes that occur in behaviors that explicitly manage, store, transfer, or cleanse sensitive information.

Potential Mitigations

• Compartmentalize the system to have “safe” areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
• Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/116.html
• https://cwe.mitre.org/data/definitions/13.html
• https://cwe.mitre.org/data/definitions/169.html
• https://cwe.mitre.org/data/definitions/22.html
• https://cwe.mitre.org/data/definitions/224.html
• https://cwe.mitre.org/data/definitions/285.html
• https://cwe.mitre.org/data/definitions/287.html
• https://cwe.mitre.org/data/definitions/290.html
• https://cwe.mitre.org/data/definitions/291.html
• https://cwe.mitre.org/data/definitions/292.html
• https://cwe.mitre.org/data/definitions/293.html
• https://cwe.mitre.org/data/definitions/294.html
• https://cwe.mitre.org/data/definitions/295.html
• https://cwe.mitre.org/data/definitions/296.html
• https://cwe.mitre.org/data/definitions/297.html
• https://cwe.mitre.org/data/definitions/298.html
• https://cwe.mitre.org/data/definitions/299.html
• https://cwe.mitre.org/data/definitions/300.html
• https://cwe.mitre.org/data/definitions/301.html
• https://cwe.mitre.org/data/definitions/302.html
• https://cwe.mitre.org/data/definitions/303.html
• https://cwe.mitre.org/data/definitions/304.html
• https://cwe.mitre.org/data/definitions/305.html
• https://cwe.mitre.org/data/definitions/306.html
• https://cwe.mitre.org/data/definitions/307.html
• https://cwe.mitre.org/data/definitions/308.html
• https://cwe.mitre.org/data/definitions/309.html
• https://cwe.mitre.org/data/definitions/310.html
• https://cwe.mitre.org/data/definitions/312.html
• https://cwe.mitre.org/data/definitions/313.html
• https://cwe.mitre.org/data/definitions/317.html
• https://cwe.mitre.org/data/definitions/318.html
• https://cwe.mitre.org/data/definitions/319.html
• https://cwe.mitre.org/data/definitions/320.html
• https://cwe.mitre.org/data/definitions/321.html
• https://cwe.mitre.org/data/definitions/322.html
• https://cwe.mitre.org/data/definitions/323.html
• https://cwe.mitre.org/data/definitions/324.html
• https://cwe.mitre.org/data/definitions/325.html
• https://cwe.mitre.org/data/definitions/326.html
• https://cwe.mitre.org/data/definitions/327.html
• https://cwe.mitre.org/data/definitions/328.html
• https://cwe.mitre.org/data/definitions/329.html
• https://cwe.mitre.org/data/definitions/330.html
• https://cwe.mitre.org/data/definitions/472.html
• https://cwe.mitre.org/data/definitions/497.html
• https://cwe.mitre.org/data/definitions/508.html
• https://cwe.mitre.org/data/definitions/573.html
• https://cwe.mitre.org/data/definitions/574.html
• https://cwe.mitre.org/data/definitions/575.html
• https://cwe.mitre.org/data/definitions/576.html
• https://cwe.mitre.org/data/definitions/577.html
• https://cwe.mitre.org/data/definitions/59.html
• https://cwe.mitre.org/data/definitions/60.html
• https://cwe.mitre.org/data/definitions/616.html
• https://cwe.mitre.org/data/definitions/643.html
• https://cwe.mitre.org/data/definitions/646.html
• https://cwe.mitre.org/data/definitions/651.html
• https://cwe.mitre.org/data/definitions/79.html

References

• https://git.kernel.org/stable/c/8ced1d242c34e342defcccdb00663354f212aae6
• https://git.kernel.org/stable/c/981ccd97f7153d310dfa92a534525bbaf46752c2
• https://git.kernel.org/stable/c/d3eb8451d529ea452740d1a2bc395a1d20c48133
• https://git.kernel.org/stable/c/f00105be6a593920e9bc7949a069d4a116888851