Libcoap
CVE-2025-34468
HIGH
Vulnerability Assessment
| Weakness |
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Stack buffer bounds checking
MITRE ATT&CK
1 technique across 1 tactic: Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
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Alert meAnalysisAIv1 – Jul 14, 2026
Availability loss and potential remote code execution in libcoap (versions up to and including 4.3.5, before commit 30db3ea) arises when attacker-controlled hostname data from a proxied CoAP URI is copied into a fixed 256-byte stack buffer during address resolution without bounds checking. A remote unauthenticated attacker can reliably crash any application that enables libcoap's proxy request handling, and may achieve code execution depending on the target's compiler hardening and runtime memory protections. There is no public exploit identified at time of analysis and it is not listed in CISA KEV; the official CVSS 4.0 base score is 8.2, but that score reflects availability impact only (VA:H, VC:N/VI:N).
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Primary rating from Vendor (vulncheck).
CVSS VectorVendor: vulncheck
DescriptionCVE.org
libcoap versions up to and including 4.3.5, prior to commit 30db3ea, contain a stack-based buffer overflow in address resolution when attacker-controlled hostname data is copied into a fixed 256-byte stack buffer without proper bounds checking. A remote attacker can trigger a crash and potentially achieve remote code execution depending on compiler options and runtime memory protections. Exploitation requires the proxy logic to be enabled (i.e., the proxy request handling code path in an application using libcoap).
Executive ViewAI
Devices and infrastructure relying on libcoap for CoAP communication (common in IoT and edge computing environments) face critical availability and security risks. Attackers can remotely crash or potentially compromise any system running libcoap 4.3.5 or earlier that has proxy handling enabled-without needing to authenticate-creating direct exposure for internet-connected deployments.
Within 24 hours, identify all systems running libcoap versions 4.3.5 and earlier that have CoAP proxy request handling enabled, prioritizing internet-facing and critical infrastructure deployments. Within 7 days, upgrade affected systems using the patch available per vendor advisory, or immediately disable CoAP proxy functionality as an interim control if upgrade timelines cannot be met. Within 30 days, verify that all production systems have received the vendor-released patch and conduct functional testing to confirm service stability.
Apply vendor patch.
Threat Intelligence Overview
NVD
CVE.org
EPSS
GitHub
VulDB
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.
A stack-based buffer overflow occurs when a program writes more data to a buffer located on the stack than it was allocated to hold.
Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.
Affected Products (CPE)CVE.org
A vulnerability was found in obgm libcoap 4.3.4. Rated high severity (CVSS 7.8), this vulnerability is low attack comple
An issue in `coap_pdu.c` in libcoap 4.3.4 allows attackers to cause undefined behavior via a sequence of messages leadin
Buffer Overflow vulnerability in coap_send function in libcoap library 4.3.1-103-g52cfd56 fixed in 4.3.1-120-ge242200 al
libcoap 4.3.1 contains a buffer over-read via the function coap_parse_oscore_conf_mem at coap_oscore.c. Rated medium sev
Out-of-bounds read in libcoap's OSCORE CBOR parsing can escalate to heap buffer overflow, enabling remote unauthenticate
A memory disclosure vulnerability exists in libcoap's OSCORE configuration parser in libcoap before release-4.3.5-patche
Null pointer dereference in coap_dtls_info_callback() in OISM libcoap 4.3.5 allows remote attackers to cause a denial of
NULL pointer dereference in coap_dtls_generate_cookie() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attack
Array index error in tls_verify_call_back() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attackers to cause
NULL pointer dereference in coap_dtls_generate_cookie() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attack
NULL pointer dereference in coap_dtls_generate_cookie() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attack
NULL pointer dereference in coap_dtls_generate_cookie() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attack
Exploit-DB