CVE-2026-99124 s390/pci: Fix leak of uninitialized kernel data in SCLP report
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-99124?
CVE-2026-99124 is a vulnerability in Linux, published on 28 Oct 2026.
Official description
In the Linux kernel, the following vulnerability has been resolved:
s390/pci: Fix leak of uninitialized kernel data in SCLP report
While report_error_write() checks that the provided buffer is at least as large as the header struct, but not that it is large enough to contain the report with the length claimed by report->length. If user-space provides a short buffer, meaning a larger report->length than the actually written payload, up to around 4K of kernel data from past the kmalloc(len + 1) sized buffer allocated in kernfs_fop_write_iter() will leak into the SCLP report.
However, as the entity processing the SCLP is privileged and able to access at least the page including the report, this does not leak data that entity could not access but it is still an out of bounds read and a malformed error report that should be rejected.
Which versions are affected by CVE-2026-99124?
How do I fix CVE-2026-99124?
Upgrade to a fixed version.
Is CVE-2026-99124 being exploited?
There is no known exploitation of CVE-2026-99124 in the wild and no public exploit code.
Sources
Also known as AZL-111230, BELL-CVE-2026-99124, DEBIAN-CVE-2026-99124, GHSA-7c6q-xh8w-h79r, UBUNTU-CVE-2026-99124.