istio: Exposure of Sensitive Information to an Unauthorized Actor
CVE-2026-31837 is a high-severity exposure of sensitive information to an unauthorized actor vulnerability in istio, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected istio versions: >= 1.29.0-alpha.0, < 1.29.1; >= 1.28.0-alpha.0, < 1.28.5; < 1.27.8. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.44% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of istio you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Istio | istio | >= 1.29.0-alpha.0, < 1.29.1; >= 1.28.0-alpha.0, < 1.28.5; < 1.27.8 | Not stated |
| Red Hat | Red Hat OpenShift AI 2.25 | Not specified in the record | Not stated |
| Red Hat | Red Hat OpenShift Service Mesh 3.0 | Not specified in the record | Not stated |
| Red Hat | Red Hat OpenShift Service Mesh 3.1 | Not specified in the record | Not stated |
| Red Hat | Red Hat OpenShift Service Mesh 3.2 | Not specified in the record | Not stated |
| Red Hat | cert-manager Operator for Red Hat OpenShift | Not specified in the record | Not stated |
| Red Hat | ExternalDNS Operator | Not specified in the record | Not stated |
| Red Hat | OpenShift Serverless | Not specified in the record | Not stated |
| Red Hat | OpenShift Service Mesh 2 | Not specified in the record | Not stated |
| Red Hat | OpenShift Service Mesh 3 | Not specified in the record | Not stated |
| Red Hat | Red Hat Ansible Automation Platform 2 | Not specified in the record | Not stated |
| Red Hat | Red Hat Connectivity Link 1 | Not specified in the record | Not stated |
| Red Hat | Red Hat OpenShift AI (RHOAI) | Not specified in the record | Not stated |
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
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- 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
- NoneNothing can be modified.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.7 | High | CNA (github.com) |
| CVSS 3.1 | 7.5 | High | NVD |
| CVSS 3.1 | 7.5 | High | CNA |
Official description
Istio is an open platform to connect, manage, and secure microservices. Prior to 1.29.1, 1.28.5, and 1.27.8, a user of Istio is impacted if the JWKS resolver becomes unavailable or the fetch fails, exposing hardcoded defaults regardless of use of the RequestAuthentication resource. This vulnerability is fixed in 1.29.1, 1.28.5, and 1.27.8.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Exposure of Sensitive Information to an Unauthorized Actor
The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
How developers prevent this class of flaw
- Compartmentalize the system to have safe areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
More Exposure of Sensitive Information to an Unauthorized Actor vulnerabilities (CWE-200)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other references
- access.redhat.com/errata/RHSA-2026:10184
- access.redhat.com/errata/RHSA-2026:5948
- access.redhat.com/errata/RHSA-2026:5950
- access.redhat.com/errata/RHSA-2026:5952
- access.redhat.com/security/cve/CVE-2026-31837
- bugzilla.redhat.com/show_bug.cgi?id=2446344
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-31837.json
Other vulnerabilities in istio
- 7.7 High severity
- 7.5 High severity
- 9.8 Critical severity
- 7.5 High severity
- 7.5 High severity
- 8.8 High severity
Recent Exposure of Sensitive Information to an Unauthorized Actor vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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