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CVE-2026-93186

Unknown

Last modified

CVE-2026-93186 is a vulnerability of currently unknown severity. In the Linux kernel, the following vulnerability has been resolved: cxl/mbox: Clamp mailbox output allocation to the payload size CXL_MEM_SEND_COMMAND bounds the user's in.size to the mailbox payload size but leaves out.size unbounded, then cxl_mbox_cmd_ctor() calls kvzalloc(out.size). A large out.size drives a huge allocation, above INT_MAX it WARNs and taints, and with panic_on_warn=1 it panics. The transport __cxl_pci_mbox_send_cmd() already clamps the response copy to min(out.size, payload_size, device len), so the output buffer is never written beyond payload_size.

Description

In the Linux kernel, the following vulnerability has been resolved: cxl/mbox: Clamp mailbox output allocation to the payload size CXL_MEM_SEND_COMMAND bounds the user's in.size to the mailbox payload size but leaves out.size unbounded, then cxl_mbox_cmd_ctor() calls kvzalloc(out.size). A large out.size drives a huge allocation, above INT_MAX it WARNs and taints, and with panic_on_warn=1 it panics. The transport __cxl_pci_mbox_send_cmd() already clamps the response copy to min(out.size, payload_size, device len), so the output buffer is never written beyond payload_size. Clamp the allocation to payload_size too, matching the RAW path.

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= 583fa5e71caeb79e04e477e9837e2f7fa53b71e4, < f5d2bbf0300f46307948864fbb97bce5097f4fe2; >= 583fa5e71caeb79e04e477e9837e2f7fa53b71e4, < 31d4841eca7c4b75751ca96d24339e19303337f2; >= 583fa5e71caeb79e04e477e9837e2f7fa53b71e4, < b4e11c731d6bee3b87315e055a1ca417c92dc1fc; >= 583fa5e71caeb79e04e477e9837e2f7fa53b71e4, < 8a13db9f899d149c3aab24abcb668121cfda5a4f
LinuxLinux5.12

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-93186?
In the Linux kernel, the following vulnerability has been resolved: cxl/mbox: Clamp mailbox output allocation to the payload size CXL_MEM_SEND_COMMAND bounds the user's in.size to the mailbox payload size but leaves out.size unbounded, then cxl_mbox_cmd_ctor() calls kvzalloc(out.size). A large out.size drives a huge allocation, above INT_MAX it WARNs and taints, and with panic_on_warn=1 it panics. The transport __cxl_pci_mbox_send_cmd() already clamps the response copy to min(out.size, payload_size, device len), so the output buffer is never written beyond payload_size. Clamp the allocation to payload_size too, matching the RAW path.
How severe is CVE-2026-93186?
Severity scoring for CVE-2026-93186 is pending analysis.
How do I fix CVE-2026-93186?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST