Monkey
CVE-2025-63651
HIGH
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V15 - Secure Coding and Architecture Memory lifecycle management
MITRE ATT&CK
2 techniques across 2 tactics: Execution, Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | CVSS 7.5 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: None. User interaction: None. Public exploit/POC available. |
| Exploit ScenarioDerived | An attacker could exploit this vulnerability to cause a Denial of Service (DoS) via sending a crafted HTTP request to the server. |
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Alert meAnalysisAIv1 – Mar 12, 2026
A use-after-free in the mk_string_char_search function (mk_core/mk_string.c) of monkey commit f37e984 allows attackers to cause a Denial of Service (DoS) via sending a crafted HTTP request to the server. [CVSS 7.5 HIGH]
RemediationAI
Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.
Affects your stack
Find out whether the stacks and servers you run are on an affected version.
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Classified as CWE-416 (Use After Free). Affects the mk_string_char_search component of Monkey. A use-after-free in the mk_string_char_search function (mk_core/mk_string.c) of monkey commit f37e984 allows attackers to cause a Denial of Service (DoS) via sending a crafted HTTP request to the server.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
Lifecycle Timeline
2DescriptionCVE.org
A use-after-free in the mk_string_char_search function (mk_core/mk_string.c) of monkey commit f37e984 allows attackers to cause a Denial of Service (DoS) via sending a crafted HTTP request to the server.
Executive ViewAI
A critical vulnerability in Monkey web server (CVE-2025-63651) allows remote attackers to crash the service through specially crafted HTTP requests, resulting in denial of service. Organizations running Monkey web server are at immediate risk of service disruption, with public exploits already available. This requires urgent mitigation until a patch is released.
Implement Web Application Firewall (WAF) rules to detect and block malformed HTTP requests targeting the mk_string_char_search function; enable rate limiting and request validation; restrict Monkey server exposure using network segmentation and firewall ACLs; deploy monitoring/alerting for unexpected service restarts; prepare rapid failover to backup web servers; disable Monkey services not critical to operations.
Threat Intelligence Overview
NVD
CVE.org
EPSS
GitHub
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Use-after-free vulnerabilities occur when a program continues to access memory through a pointer after that memory has been deallocated.
Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.
Affected Products (CPE)CVE.org
Stack-based buffer overflow in the mk_request_header_process function in mk_request.c in Monkey HTTP Daemon (monkeyd) be
The Mandril security plugin in Monkey HTTP Daemon (monkeyd) before 1.5.0 allows remote attackers to bypass access restri
An out-of-bounds read in the mk_mimetype_find function (mk_server/mk_mimetype.c) of monkey commit f37e984 allows attacke
An out-of-bounds read in the header_cmp function (mk_server/mk_http_parser.c) of monkey commit f37e984 allows attackers
An out-of-bounds read in the mk_vhost_fdt_close function (mk_server/mk_vhost.c) of monkey commit f37e984 allows attacker
A use-after-free in the mk_http_request_end function (mk_server/mk_http.c) of monkey commit f37e984 allows attackers to
An out-of-bounds read in the mk_ptr_to_buf in mk_core function (mk_memory.c) of monkey commit f37e984 allows attackers t
A NULL pointer dereference in the mk_http_range_parse function (mk_server/mk_http.c) of monkey commit f37e984 allows att
A stack overflow in the mk_http_index_lookup function (mk_server/mk_http.c) of monkey commit f37e984 allows attackers to
An out-of-bounds read in the http_parser_transfer_encoding_chunked function (mk_server/mk_http_parser.c) of monkey commi
The mk_request_header_process function in mk_request.c in Monkey 1.1.1 allows remote attackers to cause a denial of serv
Monkey HTTP Daemon (monkeyd) before 1.2.2 allows remote attackers to cause a denial of service (infinite loop) via an of
Exploit-DB