Unknown

CVE-2026-89923 — KVM: s390: Free guest debug data on vcpu destroy

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.

Published Sep 16, 2026 · Updated Oct 19, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: Linux

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.2% (30-day exploitation probability)+2

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.21%

ahead of 11% of scored CVEs · Oct 20, 2026

Affects

Linux

CVSS base

—

Score not published yet.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Linux Linux).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Linux	Linux	≥ 27291e2165b6de70c476b7b675308113edd69a60 and < 053f2068cf9b0654b651fed5ad7649d3deb982bf≥ 27291e2165b6de70c476b7b675308113edd69a60 and < 6c996b12bbe4a6023076e8eee3cfaf2cc99db76c≥ 27291e2165b6de70c476b7b675308113edd69a60 and < d6280fc540d8f4653c9b54a78cb747e128070f5e≥ 27291e2165b6de70c476b7b675308113edd69a60 and < 544a5a665019cef394ce8bda97fa7a2cab253781≥ 27291e2165b6de70c476b7b675308113edd69a60 and < 9a32c4c6a6c23b7f5bf765eb5b83ba7f64a8ec63≥ 27291e2165b6de70c476b7b675308113edd69a60 and < b5acacfdb8966abff91836c1c5bd7da59d8a526e≥ 27291e2165b6de70c476b7b675308113edd69a60 and < e4d8b7f176b976474e0800ba71ee2dfa3ce263c9≥ 27291e2165b6de70c476b7b675308113edd69a60 and < e7f698b09d4a7c36b299acf680fc50fe868e2bcd and 1 more version 3.16	Vulnerable	CVE Program (cve.org) e CISA ADP

EPSS over time FIRST

Oct 15, 2026 → Oct 20, 2026 · 5 reading(s) · max 0.21%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Not enough vector or weakness data: use the affected application’s logs as a starting point.

application logs

Timeline

What happened to this CVE, newest first.

2026
Record published
Oct 15, 2026
Affected products added · linux/linux
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Source status changed · → Received
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Sep 16, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

1× References added · Oct 19, 2026 – Oct 19, 2026
1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

10 on the record

git.kernel.org/stable/c/6c996b12bbe4a6023076e8eee3cfaf2cc99db76c
NIST National Vulnerability Database
git.kernel.org/stable/c/e7f698b09d4a7c36b299acf680fc50fe868e2bcd
NIST National Vulnerability Database
github.com/advisories/GHSA-69xh-7r26-q3mw
GitHub Security Advisories
nvd.nist.gov/vuln/detail/CVE-2026-89923
GitHub Security Advisories
git.kernel.org/stable/c/d6280fc540d8f4653c9b54a78cb747e128070f5e
NIST National Vulnerability Database
git.kernel.org/stable/c/053f2068cf9b0654b651fed5ad7649d3deb982bf
NIST National Vulnerability Database
git.kernel.org/stable/c/544a5a665019cef394ce8bda97fa7a2cab253781
NIST National Vulnerability Database
git.kernel.org/stable/c/9a32c4c6a6c23b7f5bf765eb5b83ba7f64a8ec63
NIST National Vulnerability Database
git.kernel.org/stable/c/b5acacfdb8966abff91836c1c5bd7da59d8a526e
NIST National Vulnerability Database
git.kernel.org/stable/c/e4d8b7f176b976474e0800ba71ee2dfa3ce263c9
NIST National Vulnerability Database

Elsewhere on this site

Linux
every CVE for this vendor

Related CVEs (same products)

Unknown CVE-2026-98866 sched/cache: Introduce task_struct->sched_cache_grp to fix UAF 2d
Unknown CVE-2026-98867 dm-pcache: bound the logical key offset from persistent memory 2d
Unknown CVE-2026-98868 dm-pcache: reject a kset that overruns its segment 2d
Unknown CVE-2026-98856 kprobes: Skip disarmed probes when checking optkprobe overlap 2d
Unknown CVE-2026-98857 ipvs: bound LBLCR and LBLC cache growth 2d
Unknown CVE-2026-98858 io_uring: fix task_work add use-after-free with SQPOLL 2d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No CVSS score published by NVD, the CNA, CISA or GitHub so far.
No fixed version, patch or mitigation documented.
No CISA SSVC assessment.
No CWE classification.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-89923 is "KVM: s390: Free guest debug data on vcpu destroy", rated Unknown. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. EPSS 0.21% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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