Unrated

Unauthenticated file write in OpenCost /serviceKey endpoint

IdentifiersCVE-2026-44300CWE-306

CVE-2026-44300 is an unauthenticated file write vulnerability in OpenCost affecting the /serviceKey endpoint. The flaw allows a remote attacker to overwrite or inject the Google Cloud service account key file used by the application. The issue stems from missing authentication on a sensitive administrative function that accepts service key material and writes it to disk. By abusing this endpoint, an attacker can replace trusted cloud credentials with attacker-controlled content or corrupt the existing key material, altering how OpenCost authenticates to cloud services and potentially exposing access to cloud cost and billing-related data.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can result in unauthorized overwrite of cloud service account credentials, disruption of OpenCost functionality, theft or replacement of credential material, exposure of sensitive cloud cost data, and possible privilege escalation depending on the permissions associated with the affected service account and the surrounding Kubernetes environment. If the overwritten credentials are subsequently used by the application, the attacker may be able to influence cloud API access or cause the application to operate under attacker-selected credentials.

Mitigation

If you can’t patch tonight, do this now.

Until a fixed version is deployed, restrict network access to the OpenCost service using Kubernetes NetworkPolicies or equivalent segmentation controls. Disable or remove the /serviceKey endpoint if it is not operationally required. Reduce exposure through ingress, NodePort, and port-forwarding configurations to limit remote reachability and browser-based abuse. Monitor for unexpected modification of the service account key file, and where feasible use a read-only filesystem or read-only configuration mount to prevent credential file overwrite.

Remediation

Patch, then assume compromise.

Upgrade OpenCost to version 1.119.1 or later. The vulnerable endpoint should require authentication before accepting service key updates, validate and constrain service key input, and ensure only authorized administrative workflows can modify credential files. Restrict cross-origin access to trusted origins only and review deployment configurations to confirm that credential files cannot be arbitrarily replaced through exposed application functionality.

PUBLIC EXPLOITS

Exploits

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VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

ACTIVITY FEED

Recent activity

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0 SOURCESView more in app

No public activity observed for this vulnerability.

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Exposure mapping

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Threat actor evidence

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Associated malware

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Detection signatures

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Vendor-by-vendor mapping

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Social activity