VulnerabilityPublished 28 Jul 2026Updated 17 Oct 2026

CVE-2026-62430: Xen · Accesses to the CMOS memory contents are done using an indirect IO port pair

Affects xenSource GCVE Database

Not known to be exploited · CVSS 7.5 High.

Data as of 28 Oct 2026, 05:11 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 15% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 28 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-w4qm-qcx6-wmw8

What to do

Affected software

Product	Affected	Fixed in
Ubuntu 26.10xen`pkg:deb/ubuntu/xen?arch=source&distro=stonking`Other threats	Affected =4.20.2+7-g1badcf5035-2build2 =4.20.2+37-g61ff35323e-1ubuntu1 =4.20.3+127-gc42374a105-1	Fixed in–
Ubuntu 26.04 LTSxen`pkg:deb/ubuntu/xen?arch=source&distro=resolute`Other threats	Affected =4.20.0+68-g35cb38b222-1 =4.20.2+7-g1badcf5035-2 =4.20.2+7-g1badcf5035-2build2	Fixed in–
Ubuntu 24.04 LTSxen`pkg:deb/ubuntu/xen?arch=source&distro=noble`Other threats	Affected 4.17.2-1 – 4.17.3+10-g091466ba55-1.1ubuntu3 7 affected builds	Fixed in–
Ubuntu 22.04 LTSxen`pkg:deb/ubuntu/xen?arch=source&distro=jammy`Other threats	Affected =4.11.4+24-gddaaccbbab-1ubuntu2 =4.16.0-1~ubuntu2 =4.16.0-1~ubuntu2.1	Fixed in–
Ubuntu 20.04 LTSxen`pkg:deb/ubuntu/xen?arch=source&distro=focal`Other threats	Affected 4.9.2-0ubuntu2 – 4.11.3+24-g14b62ab3e5-1ubuntu2.3 7 affected builds	Fixed in–
Ubuntu 18.04 LTSxen`pkg:deb/ubuntu/xen?arch=source&distro=bionic`Other threats	Affected =4.9.0-0ubuntu3 =4.9.0-0ubuntu4 =4.9.2-0ubuntu1	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Until a fix is available, consider restricting untrusted guest VM access or applying any recommended workarounds from the vendor.

Description

This vulnerability involves improper locking when accessing CMOS memory contents via an indirect IO port pair in Xen. Due to missing synchronization, a guest can change the cached index after it has been checked, leading to an out-of-bound read from an array. This flaw could allow unauthorized disclosure of memory contents.

Impact

An attacker controlling a guest VM could exploit this race condition to read out-of-bounds memory contents, potentially exposing sensitive information from the host or other guests. The vulnerability does not affect integrity or availability but has a high confidentiality impact.

Summary

CVE-2026-62430 describes a concurrency issue in Xen's handling of CMOS memory access. Xen caches the guest-chosen index for indirect IO port access, but one usage path lacks the necessary locking to prevent concurrent modifications. Consequently, a guest VM can alter the index after validation, causing an out-of-bounds read from an array. This vulnerability is categorized under CWE-362 (Race Condition) and has a CVSS 3.1 vector indicating network attack vector, low attack complexity, no privileges required, no user interaction, unchanged scope, and high confidentiality impact.

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') (opens in a new tab)
Class weaknessLikelihood of exploit: MediumOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
Architecture and Design
In languages that support it, use synchronization primitives. Only wrap these around critical code to minimize the impact on performance.
Architecture and Design
Use thread-safe capabilities such as the data access abstraction in Spring.
Architecture and Design
Minimize the usage of shared resources in order to remove as much complexity as possible from the control flow and to reduce the likelihood of unexpected conditions occurring.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
Secure Design Principles (opens in a new tab)
OWASP ASVS 4.0.3
V1.11.2 (opens in a new tab)
Attack patterns
Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions (opens in a new tab)
Leveraging Race Conditions (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 29 Jul 2026, 11:24 UTC

WeaknessesCWE-362

Technical details

References

Community reviews

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