CVE-2026-88858
Description
A flaw was found in Grafana. An authenticated user, including one with basic viewer privileges, can cause a Denial of Service (DoS) by submitting deeply nested mathematical expressions that crash the server. Additionally, an authorized user can incorporate such expressions into alert rules, causing the service crash to repeat continuously across restarts.
Statement
This issue is rated Moderate per upstream Grafana Labs (CVSS 6.5). An authenticated user with Viewer privileges can crash the Grafana server by submitting a crafted server-side math expression that triggers uncontrolled recursion. A user who can provision alert rules can make the outage persist across restarts. Confidentiality and integrity are not affected.
Mitigation
Disable server-side expressions in the Grafana configuration:
1. Edit `/etc/grafana/grafana.ini` and set the following configuration under the `[expressions]` block:
ini
[expressions]
enabled = false
2. Restart the Grafana service:
bash
systemctl restart grafana-server
Caveats:
Disabling expressions completely disables server-side math expressions as well as all expression-based alert rules.
Warning: Restarting the `grafana-server` service will cause a temporary interruption of service for active sessions.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.5 | N/A | 6.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Red Hat CVSS v3 Score Explanation
Aligned with upstream Grafana / NVD CVSS 6.5 Medium (Viewer DoS via crafted server-side math expression).
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
When allocating resources without limits, an attacker could prevent other systems, applications, or processes from accessing the same type of resource. It can be easy for an attacker to consume many resources by rapidly making many requests or causing larger resources to be used than is needed.
Frequently Asked Questions
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