CVE-2025-63651Public exploitNetwork attack vector

Unauthenticated server crash via freed-memory access

Published Jan 29, 2026 · Updated Jan 29, 2026

Use-after-free in Monkey HTTP Server through commit f37e984 allows remote attackers to crash the server with a crafted HTTP request. The mk_string_char_search function in mk_core/mk_string.c accesses freed memory while processing attacker-controlled request data. No authentication or user interaction is required; the published impact is a service crash, with no reported data disclosure or code execution.

CVSS severity7.5
High
EPSS probability0.94%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Monkey HTTP Server through commit f37e984 allows remote attackers to crash the server with a crafted HTTP request. The mk_string_char_search function in mk_core/mk_string.c accesses freed memory while processing attacker-controlled request data. No authentication or user interaction is required; the published impact is a service crash, with no reported data disclosure or code execution.

The record

CVE
CVE-2025-63651
Published
Jan 29, 2026
Updated
Jan 29, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-416, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 29, 2026Record 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 privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-416Use After Free
T1499.004Endpoint Denial of Service: Application or System Exploitation

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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