VulnerabilityPublished 24 Nov 2025

CVE-2025-65495: libcoap · CVE-2025-65495 is a high-severity

Affects libcoapSource CVE Database V5

Not known to be exploited · CVSS 7.5 High.

Data as of 26 Oct 2026, 11:07 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 17% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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 26 Oct 2026.

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 or the CVSS exploit maturity 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
GitHubobgm/libcoap`pkg:github/obgm/libcoap`Other threats	Affected =4.3.5	Fixed in–

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AI-suggested

Monitor official libcoap repositories and security advisories closely for patches or updates addressing CVE-2025-65495 and apply them promptly once available.
Implement network-level filtering to detect and block malformed or suspicious TLS certificates that could exploit the vulnerability, using intrusion detection/prevention systems (IDS/IPS) with updated signatures.
Employ strict certificate validation policies and consider additional certificate sanity checks before passing certificates to vulnerable libcoap components.
Where feasible, isolate or segment IoT and constrained device networks to limit exposure to untrusted sources that might attempt exploitation.
Conduct thorough inventory and risk assessments to identify all systems using libcoap 4.3.5 and evaluate their exposure.
Develop and test incident response plans to quickly recover from potential denial of service incidents caused by this vulnerability.
Consider temporary mitigations such as disabling TLS certificate verification in controlled environments if acceptable, until patches are available.
Engage with vendors and device manufacturers to confirm their mitigation plans and timelines for addressing this vulnerability in embedded products.

Description

CVE-2025-65495 is a high-severity vulnerability in the OISM libcoap 4.3.5 library, caused by an integer signedness error in the tls_verify_call_back() function. This flaw allows remote attackers to trigger a denial of service by sending a specially crafted TLS certificate that causes the i2d_X509() function to return -1, which is then incorrectly used as a malloc() size parameter. Exploitation requires no authentication or user interaction and can be performed remotely over the network. The vulnerability impacts the availability of applications using the affected libcoap version, potentially causing crashes or service interruptions. No known exploits are currently reported in the wild, and no patches have been published yet. European organizations relying on libcoap 4.3.5 in IoT, constrained devices, or CoAP-based communication systems are at risk.

Impact

The primary impact of CVE-2025-65495 is a denial of service condition caused by application crashes or service interruptions when processing malicious TLS certificates. For European organizations, especially those deploying IoT devices, smart city infrastructure, industrial control systems, or other constrained network environments using libcoap 4.3.5, this vulnerability poses a risk to operational continuity and availability. Disruptions could affect critical services such as energy management, transportation systems, healthcare devices, and building automation. The remote and unauthenticated nature of the exploit increases the risk of widespread attacks, potentially leading to network segmentation issues or cascading failures in interconnected systems. While confidentiality and integrity are not directly impacted, the loss of availability can have significant operational and financial consequences. The absence of known exploits in the wild offers a window for proactive mitigation, but the lack of patches necessitates immediate defensive measures. Organizations relying on CoAP-based communication should assess their exposure and prepare for incident response scenarios involving unexpected service outages.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 1 Dec 2025, 14:42 UTC

WeaknessesCWE-195

Technical details

References

Community reviews

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