How severe is CVE-2026-42487?

CVE-2026-42487 has a CVSS 3.x base score of 7.9, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability high.

Is CVE-2026-42487 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (1st percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-42487?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-42487 have an EU (EUVD) identifier?

Yes. CVE-2026-42487 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-37888.

When was CVE-2026-42487 published?

CVE-2026-42487 was published on 2026-06-18 and last updated on 2026-06-22.

CVE-2026-42487

CVE-2026-42487 is a high-severity vulnerability with a CVSS 3.x base score of 7.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-362.

Key facts

Severity: High (CVSS 3.x base score 7.9)
EPSS exploit prediction: 0% (1st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-37888
Weakness: CWE-362
Published: 2026-06-18
Last modified: 2026-06-22

Description

HVM guest I/O port accesses are subject to either emulation or at least translation. Translations are managed by the device model (via XEN_DOMCTL_ioport_mapping), and hence the linked list used may changed at any time. Traversal of those lists (while handling guest I/O port accesses) therefore needs synchronizing with updates, which was missing so far.

Frequently asked questions

What is CVE-2026-42487?: HVM guest I/O port accesses are subject to either emulation or at least translation. Translations are managed by the device model (via XEN_DOMCTL_ioport_mapping), and hence the linked list used may changed at any time. Traversal of those lists (while handling guest I/O port accesses) therefore needs synchronizing with updates, which was missing so far.
How severe is CVE-2026-42487?: CVE-2026-42487 has a CVSS 3.x base score of 7.9, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability high.
Is CVE-2026-42487 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (1st percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-42487?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-42487 have an EU (EUVD) identifier?: Yes. CVE-2026-42487 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-37888.
When was CVE-2026-42487 published?: CVE-2026-42487 was published on 2026-06-18 and last updated on 2026-06-22.

References

Other CWE-362 (Race Condition) vulnerabilities

CVE-2022-27626 — Critical (CVSS 10.0): A vulnerability regarding concurrent execution using shared resource with improper synchronization ('Race Condition')…
CVE-2015-8556 — Critical (CVSS 10.0): Local privilege escalation vulnerability in the Gentoo QEMU package before 2.5.0-r1.
CVE-2014-0703 — Critical (CVSS 10.0): Cisco Wireless LAN Controller (WLC) devices 7.4 before 7.4.110.0 distribute Aironet IOS software with a race condition…
CVE-2010-1228 — Critical (CVSS 10.0): Multiple race conditions in the sandbox infrastructure in Google Chrome before 4.1.249.1036 have unspecified impact and…
CVE-2008-6598 — Critical (CVSS 10.0): Multiple race conditions in WANPIPE before 3.3.6 have unknown impact and attack vectors related to "bri restart logic."
CVE-2026-46137 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: mptcp: pm: ADD_ADDR rtx: fix potential…

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