CVE-2025-65503VulnerabilityPublished 24 Nov 2025

CVE-2025-65503: async_mqtt · n/a

Affects async_mqttSource CVE Database V5

Not known to be exploited · CVSS 7.5 High : upgrade to 10.2.5 soon.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 14% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 10.2.5

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

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

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, 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: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 24 Nov 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

Upgrade redboltz/async_mqtt to 10.2.5.

Affected software

Product	Affected	Fixed in
GitHubredboltz/async_mqtt`pkg:github/redboltz/async_mqtt`Other threats	Affected <10.2.5	Fixed in 10.2.5

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

1. 2. In the absence of patches, implement strict network segmentation and firewall rules to restrict access to MQTT brokers and endpoints, limiting exposure to untrusted networks. 3. Employ SSL/TLS configuration best practices to minimize the chance of SSL initialization failures, such as using validated certificates and robust cipher suites. 4. Conduct code reviews and testing to verify proper object lifecycle management in custom integrations using async_mqtt, ensuring that destruction order issues are addressed. 5. Deploy runtime protections such as memory safety tools (e.g., AddressSanitizer) during development and testing phases to detect use-after-free conditions. 6. Monitor MQTT traffic and system logs for anomalies or repeated connection failures that may indicate exploitation attempts. 7. Prepare incident response plans to quickly isolate and remediate affected systems in case of DoS attacks leveraging this vulnerability.

Description

Use after free in endpoint destructors in Redboltz async_mqtt 10.2.5 allows local users to cause a denial of service via triggering SSL initialization failure that results in incorrect destruction order between io_context and endpoint objects.

Impact

For European organizations, the primary impact of CVE-2025-65503 is the potential for denial of service in systems using the vulnerable async_mqtt library. This can disrupt IoT device communication, industrial control systems, and messaging platforms that rely on MQTT protocols, leading to operational downtime and service unavailability. Critical infrastructure sectors such as manufacturing, energy, transportation, and smart city deployments that depend on MQTT for telemetry and control could experience interruptions. Although the vulnerability does not compromise data confidentiality or integrity, the loss of availability can have cascading effects on business continuity and safety systems. The ease of exploitation and lack of required privileges increase the risk of widespread disruption, especially in environments with remote access or exposed MQTT endpoints. European organizations with large-scale IoT deployments or those integrating async_mqtt in their middleware stacks should be particularly vigilant.

CWE-416Use After Free (opens in a new tab)
Variant weaknessLikelihood of exploit: HighCWE Top 25 (2025): #7
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
Architecture and Design · Language Selection
Choose a language that provides automatic memory management.
Implementation · Attack Surface Reduction
When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 1 Dec 2025, 14:38 UTC

WeaknessesCWE-416

Technical details

References

Community reviews

Related threats