Monkey: Out-of-bounds Read
CVE-2025-63649 is a high-severity out-of-bounds read vulnerability in Monkey from Monkey-project, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Monkey versions: 1.8.5 and earlier. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.03% chance of exploitation within 30 days, higher than 64% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of Monkey you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Monkey-project | Monkey | 1.8.5 and earlier | Not stated |
Version data comes from NVD's product matching. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CISA (ADP).
Official description
An out-of-bounds read in the http_parser_transfer_encoding_chunked function (mk_server/mk_http_parser.c) of monkey commit f37e984 allows attackers to cause a Denial of Service (DoS) via sending a crafted POST request to the server.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that provides appropriate memory abstractions.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- github.com/archersec/security-advisories/blob/master/monkey/monkey-advisory-2025.mdExploit, Third Party Advisory
Technical write-ups (may include proof of concept)
- github.com/monkey/monkey/issues/426Exploit, Issue Tracking
Other vulnerabilities in Monkey
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
Recent Out-of-bounds Read vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 8.1 High severity
- 10.0 Critical severity
- 9.3 Critical severity
- 9.3 Critical severity
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