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CVE-2026-89924: KVM: s390: Fix old_data leak in guest debug error path

• Severity: unknown
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-16 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: KVM: s390: Fix old_data leak in guest debug error path __import_wp_info() allocates a per-watchpoint old_data buffer to back up the original guest memory contents. If a later watchpoint of the same KVM_SET_GUEST_DEBUG request fails to import, kvm_s390_import_bp_data() jumps to the error label, which frees the wp_info array but not the old_data buffers of the entries that were imported successfully. Up to MAX_BP_COUNT - 1 buffers of up to MAX_WP_SIZE bytes are leaked per failed request, and the request can be repeated. Create error handling for cleaning up all created old_data memory areas.

Affected products

• Linux kernel: 3.16 — fixed in 7.3

How to fix

Upgrade to a fixed version: Linux kernel 7.3. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/124c81ee610e1fbdd93d4399f88d9e28ba97a941
• https://git.kernel.org/stable/c/4048d0a252163084794be3e37995b872c5178913
• https://git.kernel.org/stable/c/46cb8a273e2f853f89a78b59dbdff8787b6e1c86
• https://git.kernel.org/stable/c/5fbf319137735252eefa507193c9a619af5b7457
• https://git.kernel.org/stable/c/aa9c8e8baf1e765fa65b93212522c636f25d846f
• https://git.kernel.org/stable/c/c85d402553987777cc4742751437ea5dcbf98a7b
• https://git.kernel.org/stable/c/e5ae7816e5ad145618f7fd568a0e8a94dd9f81f4
• https://git.kernel.org/stable/c/f55e4d415d95342d5753e528e05a1e8623992c3f

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