CVE-2025-6566VulnerabilityPublished 24 Jun 2025

CVE-2025-6566: oatpp Oat++ · Stack-based Buffer Overflow

Affects oatpp Oat++Source CVE Database V5

Not known to be exploited · CVSS 6.9 Medium.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 4.0 base score

6.9Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.7% chance of exploitation in 30 days – higher than 56% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P

Base metrics

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Threat metrics

Exploit Maturity: POC

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.
Exploit Maturity: POC: Based on threat intelligence sources each of the following must apply: · Proof-of-concept is publicly available · No knowledge of reported attempts to exploit this vulnerability · No knowledge of publicly available solutions used to simplify attempts to exploit the vulnerability

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 24 Jun 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
GitHuboatpp/oatpp`pkg:github/oatpp/oatpp`Other threats	Affected =1.3.0 =1.3.1	Fixed in–

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AI-suggested

1. Immediate upgrade: Organizations should upgrade to a patched version of Oat++ once available. 2. Input sanitization: Implement strict validation and sanitization of JSON inputs before they reach the deserializeArray function to prevent malformed or malicious payloads. 3. Runtime protections: Employ compiler-level security features such as stack canaries, Address Space Layout Randomization (ASLR), and Control Flow Integrity (CFI) to mitigate exploitation impact. 4. Network controls: Restrict access to services using Oat++ to trusted networks or VPNs, and deploy Web Application Firewalls (WAFs) with custom rules to detect and block suspicious JSON payloads targeting deserialization. 5. Monitoring and detection: Enable detailed logging and monitor for anomalous behavior or crashes related to JSON deserialization. Use intrusion detection systems to identify potential exploitation attempts. 6. Code review and testing: Conduct thorough security reviews and fuzz testing of deserialization code paths to identify and remediate similar vulnerabilities proactively. 7. Incident response readiness: Prepare response plans for potential exploitation scenarios, including isolating affected systems and forensic analysis.

Description

A vulnerability was found in oatpp Oat++ up to 1.3.1. It has been declared as critical. This vulnerability affects the function deserializeArray of the file src/oatpp/json/Deserializer.cpp. The manipulation leads to stack-based buffer overflow. The attack can be initiated remotely. The exploit has been disclosed to the public and may be used.

Impact

For European organizations, the impact of CVE-2025-6566 can be significant, especially for those utilizing Oat++ in their web services, APIs, or embedded systems. Exploitation could lead to unauthorized remote code execution, allowing attackers to compromise sensitive data, disrupt service availability, or pivot within internal networks. Industries such as finance, healthcare, telecommunications, and critical infrastructure, which often deploy microservices and high-performance APIs, may face increased risks. The vulnerability could also affect cloud service providers and SaaS platforms based in Europe that incorporate Oat++ in their technology stacks. Given the remote exploitability without authentication, attackers could target exposed endpoints to gain initial access or cause denial of service. This could result in data breaches, operational downtime, regulatory non-compliance (e.g., GDPR), and reputational damage. The medium CVSS score reflects a balance between ease of exploitation and impact; however, the critical nature of buffer overflows and potential for code execution warrants urgent attention.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 24 Jun 2025, 13:25 UTC

Technical details

References

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