VulnerabilityPublished 9 Oct 2024Updated 10 Oct 2024

CVE-2024-46304: libcoap · Classic Buffer Overflow

Affects libcoapSource CVE Database V5

Not known to be exploited · CVSS 7.5 High.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 0.5% chance of exploitation in 30 days – higher than 46% 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 9 Oct 2024
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-rc2	Fixed in–

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

AI-suggested

To mitigate CVE-2024-46304, organizations should first identify all systems and devices using libcoap versions 4.3.5-rc2 or earlier. Since no official patches are currently linked, users should monitor libcoap project repositories and vendor advisories for updates or security patches addressing this issue. In the interim, network-level mitigations can reduce exposure: restrict access to CoAP services using firewalls or network segmentation to limit exposure to untrusted networks. Implement rate limiting and anomaly detection on CoAP traffic to detect and block malformed or suspicious PUT block requests. For embedded devices, consider disabling or restricting block-wise transfer features if not required. Conduct thorough testing of firmware or software updates incorporating newer libcoap versions once available. Additionally, maintain comprehensive logging and monitoring of CoAP traffic to detect potential exploitation attempts early. Organizations should also evaluate fallback or redundancy mechanisms to maintain service continuity in case of DoS events. Finally, engage with device manufacturers and vendors to ensure timely updates and coordinated vulnerability response.

Description

A NULL pointer dereference in libcoap v4.3.5-rc2 and below allows a remote attacker to cause a denial of service via the coap_handle_request_put_block function in src/coap_block.c.

Impact

The primary impact of CVE-2024-46304 is a denial of service condition caused by crashing the libcoap process handling CoAP requests. This can disrupt communication in IoT devices, embedded systems, and industrial control systems that rely on libcoap for CoAP protocol implementation. The loss of availability can lead to operational downtime, loss of telemetry data, interruption of automated control processes, and potential cascading failures in dependent systems. Since the vulnerability is remotely exploitable without authentication, attackers can target exposed CoAP endpoints to cause widespread service outages. This is particularly critical in environments where CoAP is used for critical infrastructure monitoring, smart city applications, or medical devices. Although confidentiality and integrity are not directly impacted, the availability disruption can have severe consequences in time-sensitive or safety-critical deployments. The lack of known exploits currently reduces immediate risk, but the vulnerability’s characteristics make it a likely candidate for future exploitation attempts. Organizations with large IoT deployments or industrial networks using libcoap should consider this a high-priority threat.

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #11
The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Operation · Build and Compilation · Environment Hardening
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index…
OWASP Cheat Sheets
Docker Security (opens in a new tab)
XML Security (opens in a new tab)
OWASP ASVS 4.0.3
V5.4.1 (opens in a new tab)
V14.1.2 (opens in a new tab)
V13.3.1 (opens in a new tab)
Attack patterns
Buffer Overflow via Environment Variables (opens in a new tab)
Overflow Buffers (opens in a new tab)
Client-side Injection-induced Buffer Overflow (opens in a new tab)
Filter Failure through Buffer Overflow (opens in a new tab)
MIME Conversion (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/obgm/libcoap/issues/1509 (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Feb 2026, 08:31 UTC

WeaknessesCWE-120

Technical details

References

Community reviews

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