Linux Kernel up to 7.2.4 s390 KVM Debug kvm_s390_clear_bp_data memory leak

CVSS Meta Temp Score
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CTI Interest Score
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4.2$0-$5k0.45

Summaryinfo

A vulnerability, which was classified as problematic, was found in Linux Kernel up to 7.2.4. The impacted element is the function kvm_s390_clear_bp_data of the component s390 KVM Debug. Such manipulation leads to memory leak. This vulnerability is traded as CVE-2026-89923. An attack has to be approached locally. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.2.4. It has been rated as problematic. Affected by this issue is the function kvm_s390_clear_bp_data of the component s390 KVM Debug. The manipulation with an unknown input leads to a memory leak vulnerability. Using CWE to declare the problem leads to CWE-401. The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory. Impacted is availability. CVE summarizes:

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.

The advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2026-89923 since 09/11/2026. The exploitation is known to be easy. The attack needs to be approached locally. Additional levels of successful authentication are needed for exploitation. There are known technical details, but no exploit is available.

Upgrading to version 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, 6.18.51, 7.2.5 or 7.3-rc1 eliminates this vulnerability. Applying the patch 053f2068cf9b0654b651fed5ad7649d3deb982bf/6c996b12bbe4a6023076e8eee3cfaf2cc99db76c/d6280fc540d8f4653c9b54a78cb747e128070f5e/544a5a665019cef394ce8bda97fa7a2cab253781/9a32c4c6a6c23b7f5bf765eb5b83ba7f64a8ec63/b5acacfdb8966abff91836c1c5bd7da59d8a526e/e4d8b7f176b976474e0800ba71ee2dfa3ce263c9/e7f698b09d4a7c36b299acf680fc50fe868e2bcd is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.4
VulDB Meta Temp Score: 4.2

VulDB Base Score: 4.4
VulDB Temp Score: 4.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Memory leak
CWE: CWE-401 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.270/5.15.221/6.1.188/6.6.157/6.12.110/6.18.51/7.2.5/7.3-rc1
Patch: 053f2068cf9b0654b651fed5ad7649d3deb982bf/6c996b12bbe4a6023076e8eee3cfaf2cc99db76c/d6280fc540d8f4653c9b54a78cb747e128070f5e/544a5a665019cef394ce8bda97fa7a2cab253781/9a32c4c6a6c23b7f5bf765eb5b83ba7f64a8ec63/b5acacfdb8966abff91836c1c5bd7da59d8a526e/e4d8b7f176b976474e0800ba71ee2dfa3ce263c9/e7f698b09d4a7c36b299acf680fc50fe868e2bcd

Timelineinfo

09/11/2026 CVE reserved
09/16/2026 +5 days Advisory disclosed
09/16/2026 +0 days VulDB entry created
09/16/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-89923 (🔒)
GCVE (CVE): GCVE-0-2026-89923
GCVE (VulDB): GCVE-100-405764

Entryinfo

Created: 09/16/2026 14:43
Changes: 09/16/2026 14:43 (59)
Complete: 🔍
Cache ID: 216::103

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