CVE-2026-6388
Raw vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:H/A:LSummary
CVE-2026-6388 is a critical-severity Insufficient Granularity of Access Control (CWE-1220) vulnerability in Redhat (inferred from references). Its CVSS base score is 9.1 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Services File Permissions Weakness (T1574.010); ranked at the 29th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to AC-24 (Access Control Decisions) and AC-3 (Access Enforcement) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-6388 is a critical vulnerability (CVSS 9.1, CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:H/A:L) in ArgoCD Image Updater, published on 2026-04-15T22:17:22.583 and associated with CWE-1220. The flaw arises from insufficient validation in the ImageUpdater resource, enabling attackers to bypass namespace boundaries in multi-tenant Kubernetes environments. This affects deployments relying on ArgoCD Image Updater for automated image updates in GitOps workflows.
An attacker with low-privilege access—specifically, permissions to create or modify an ImageUpdater resource within their own namespace—can exploit this issue remotely with low complexity and no user interaction. Successful exploitation allows triggering unauthorized image updates on applications managed by other tenants, resulting in cross-namespace privilege escalation. This compromises application integrity by enabling malicious image deployments across boundaries.
Mitigation details are available in the referenced advisories, including the Red Hat security bulletin at https://access.redhat.com/security/cve/CVE-2026-6388 and the Bugzilla tracker at https://bugzilla.redhat.com/show_bug.cgi?id=2458766, which outline patches and workarounds for affected ArgoCD Image Updater versions.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-23126
Vulnerability Data
A flaw was found in ArgoCD Image Updater. This vulnerability allows an attacker, with permissions to create or modify an ImageUpdater resource in a multi-tenant environment, to bypass namespace boundaries. By exploiting insufficient validation, the attacker can trigger unauthorized image…
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updates on applications managed by other tenants. This leads to cross-namespace privilege escalation, impacting application integrity through unauthorized application updates.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 4 hardening rules · 4 OS baselines
V16.4.2V8.4.2V11.7.1V13.2.4
Mitigating Controls (NIST 800-53 r5) AI
Least privilege explicitly demands that only the minimum necessary accesses are granted, eliminating the broad permissions that define this weakness.
AC-24 requires access decisions to be applied precisely and unambiguously to every request, structurally blocking insufficiently granular policies.
AC-3 requires enforcement of authorizations according to policy, directly compelling sufficiently granular rules so broad allowances cannot be introduced.
AC-4 enforces approved information flows with explicit source/destination rules, preventing overly coarse access policies from being deployed.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
PR.IR-01's segmentation + zero-trust rules directly enforce minimum-necessary access at network boundaries, removing most instances of overly broad policy; CWE-1220 can still exist in application-layer or intra-segment controls that this single outcome does not address.
PR.PS-06's general SDLC practices can surface granularity issues during design/review (partial prevention) but do not specifically target access-control policy breadth, so they remove only part of CWE-1220's risk.
CWE-1220 permits unauthorized access to sensitive assets but neither prevents nor impairs the delivery of adverse-event information to authorized recipients.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Directly requires information-access restriction at the level of individual assets and operations, addressing the granularity gap.
Establishes the overarching access-control policy whose granularity directly determines whether the weakness exists.
Defines the assignment and review of access rights; insufficient granularity in those rights is the root of CWE-1220.
Specifies management of privileged access rights, where overly broad privileges are a common manifestation of the weakness.
Limits use of privileged utilities; overly coarse access rules can still allow unauthorized utility access.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Windows Server 2016 (1 rule)
- V-225025 Local accounts with blank passwords must be restricted to prevent access from the network. prevents CWE-1220
Windows Server 2022 (1 rule)
- V-254446 Windows Server 2022 must prevent local accounts with blank passwords from being used from the network. prevents CWE-1220