xen-orchestra: Improperly Controlled Modification of Object Prototype Attributes
CVE-2026-110111 is a high-severity improperly controlled modification of object prototype attributes vulnerability in xen-orchestra from Vatesfr, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists version 6.9.0 as the first without the flaw, so updating xen-orchestra to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.62% chance of exploitation within 30 days, higher than 50% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update xen-orchestra to 6.9.0 or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Vatesfr | xen-orchestra | before 6.9.0 | 6.9.0 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (vulncheck.com).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 7.7 | High | CNA (vulncheck.com) |
| CVSS 3.1 | 7.5 | High | CNA (vulncheck.com) |
Official description
Xen Orchestra before 6.9.0 contains an improper access control vulnerability that allows any authenticated user to become global administrator by abusing the unprotected vm.importFromEsxi and vm.importMultipleFromEsxi methods. Attackers can point xo-server at a malicious ESXi host serving a crafted .vmx file with __proto__.permission set, polluting Object.prototype so permission-less accounts inherit admin rights and enabling remote code execution.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improperly Controlled Modification of Object Prototype Attributes
The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.
How developers prevent this class of flaw
- By freezing the object prototype first (for example, Object.freeze(Object.prototype)), modification of the prototype becomes impossible.
- By blocking modifications of attributes that resolve to object prototype, such as proto or prototype, this weakness can be mitigated.
- When handling untrusted objects, validating using a schema can be used.
More Improperly Controlled Modification of Object Prototype Attributes vulnerabilities (CWE-1321)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
Recent Improperly Controlled Modification of Object Prototype Attributes vulnerabilities
- 8.2 High severity
- 8.9 High severity
- 9.3 Critical severity
- 8.2 High severity
- 9.5 Critical severity
- 9.2 Critical severity
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