CVE-2025-66303Public exploitNetwork attack vector

Admin-panel denial of service via malformed cron expression

Published Dec 1, 2025 · Updated Dec 3, 2025

Denial of service in GetGrav Grav before 1.8.0-beta.27 allows remote authenticated users to disable the admin panel via scheduled_at. Scheduler paths pass the persisted expression to CronExpression::factory without handling InvalidArgumentException, so malformed input breaks panel rendering. Administrator privileges are required, and the invalid value stored in backup.yaml prevents subsequent administrative use.

CVSS severity4.9
Medium
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in GetGrav Grav before 1.8.0-beta.27 allows remote authenticated users to disable the admin panel via scheduled_at. Scheduler paths pass the persisted expression to CronExpression::factory without handling InvalidArgumentException, so malformed input breaks panel rendering. Administrator privileges are required, and the invalid value stored in backup.yaml prevents subsequent administrative use.

The record

CVE
CVE-2025-66303
Published
Dec 1, 2025
Updated
Dec 3, 2025
Vendor
GetGrav
Product
Grav
Classifications
CWE-400, T1499
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Dec 1, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 3, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.8.0-beta.27

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

GetGrav · Gravversion=< 1.8.0-beta.27

Published CVSS scores

4.9GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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