CVE-2025-63721Public exploitNetwork attack vector

Authenticated code execution via unsafe YAML deserialization

Published Dec 8, 2025 · Updated Dec 11, 2025

Insecure deserialization in HummerRisk 1.5.0 and earlier allows remote authenticated users to execute code via /rule/add. The endpoint deserializes attacker-supplied YAML with bundled SnakeYAML 1.33 without restricting constructed types, enabling arbitrary file writes. A normal user account is sufficient, and overwriting /etc/crontab yields command execution with control of the server.

CVSS severity8.8
High
EPSS probability0.49%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insecure deserialization in HummerRisk 1.5.0 and earlier allows remote authenticated users to execute code via /rule/add. The endpoint deserializes attacker-supplied YAML with bundled SnakeYAML 1.33 without restricting constructed types, enabling arbitrary file writes. A normal user account is sufficient, and overwriting /etc/crontab yields command execution with control of the server.

The record

CVE
CVE-2025-63721
Published
Dec 8, 2025
Updated
Dec 11, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-502, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 8, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 11, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 11, 2026Sep 17, 2026
Latest reporting daySep 17, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
T1190Exploit Public-Facing Application

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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