KVM: s390: Free guest debug data on vcpu destroy
Key facts
- Attack vector
- —
- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
- —
- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 6 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
In the Linux kernel, the following vulnerability has been resolved: KVM: s390: Free guest debug data on vcpu destroy kvm_s390_clear_bp_data() is only called from kvm_arch_vcpu_ioctl_set_guest_debug(), i.e. when user space changes or disables debugging. A vCPU that is destroyed while hardware breakpoints are still armed - the normal case when the VMM just exits or crashes - leaks hw_bp_info, hw_wp_info and all old_data buffers, since generic KVM frees the vCPU right after kvm_arch_vcpu_destroy(). That is bounded by MAX_BP_COUNT entries, so roughly 8 KiB per vCPU, but it is unbounded over VM lifetimes. The allocations are GFP_KERNEL_ACCOUNT, so the charge also outlives the exiting process and pins dying memcgs. Fix by clearing the debug data on vCPU destruction. Calling it unconditionally is fine: struct kvm_vcpu is zero allocated, so for a vCPU that never enabled debugging the counters are 0 and the pointers NULL.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
- Fix · CNA Linux (Linux) Fixed in 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, 6.18.51, 7.2.5, 7.3
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
Not affected: 1 product
- Red Hat Enterprise Linux 7
Timeline
- 2026-10-02 Threatist record created from CVE-2026-89923
- 2026-10-03 Alias added: GHSA-69xh-7r26-q3mw
- 2026-10-06 Affected versions changed · Red Hat
- 2026-10-06 CVSS score added · Red Hat
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-11-07 Affected versions changed · Red Hat
References
Other 8
- https://git.kernel.org/stable/c/053f2068cf9b0654b651fed5ad7649d3deb982bf
- https://git.kernel.org/stable/c/6c996b12bbe4a6023076e8eee3cfaf2cc99db76c
- https://git.kernel.org/stable/c/d6280fc540d8f4653c9b54a78cb747e128070f5e
- https://git.kernel.org/stable/c/544a5a665019cef394ce8bda97fa7a2cab253781
- https://git.kernel.org/stable/c/9a32c4c6a6c23b7f5bf765eb5b83ba7f64a8ec63
- https://git.kernel.org/stable/c/b5acacfdb8966abff91836c1c5bd7da59d8a526e
- https://git.kernel.org/stable/c/e4d8b7f176b976474e0800ba71ee2dfa3ce263c9
- https://git.kernel.org/stable/c/e7f698b09d4a7c36b299acf680fc50fe868e2bcd
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Sources
- CVE-2026-89923 · CVE Program
- CVE-2026-89923 · NVD
- FIRST EPSS
- GHSA-69xh-7r26-q3mw · GitHub Advisory Database · CC BY 4.0
- CVE-2026-89923 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences