CVE-2025-34468

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).

CVSS v3 9.8 CRITICAL

9.8^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/obgm/libcoap/commit/30db3ea	Patch
https://github.com/obgm/libcoap/pull/1737	Issue Tracking
https://libcoap.net/	Product
https://www.vulncheck.com/advisories/libcoap-stack-based-buffer-overflow-in-address-resolution-dos-or-potential-rce	Third Party Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:libcoap:libcoap:*:*:*:*:*:*:*:*

History

14 Jan 2026, 20:18

Type	Values Removed	Values Added
CWE		CWE-787
CPE		cpe:2.3:a:libcoap:libcoap::::::::
First Time		Libcoap Libcoap libcoap
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 9.8
References	~~() https://github.com/obgm/libcoap/commit/30db3ea -~~	() https://github.com/obgm/libcoap/commit/30db3ea - Patch
References	~~() https://github.com/obgm/libcoap/pull/1737 -~~	() https://github.com/obgm/libcoap/pull/1737 - Issue Tracking
References	~~() https://libcoap.net/ -~~	() https://libcoap.net/ - Product
References	~~() https://www.vulncheck.com/advisories/libcoap-stack-based-buffer-overflow-in-address-resolution-dos-or-potential-rce -~~	() https://www.vulncheck.com/advisories/libcoap-stack-based-buffer-overflow-in-address-resolution-dos-or-potential-rce - Third Party Advisory

31 Dec 2025, 19:15

Type	Values Removed	Values Added
New CVE

Information

Published : 2025-12-31 19:15

Updated : 2026-01-14 20:18

NVD link : CVE-2025-34468

Mitre link : CVE-2025-34468

CVE.ORG link : CVE-2025-34468

JSON object : View

Products Affected

libcoap

libcoap

CWE

CWE-121

Stack-based Buffer Overflow

CWE-787

Out-of-bounds Write

{"id": "CVE-2025-34468", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 9.8, "attackVector": "NETWORK", "baseSeverity": "CRITICAL", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 5.9, "exploitabilityScore": 3.9}], "cvssMetricV40": [{"type": "Secondary", "source": "disclosure@vulncheck.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 8.2, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "HIGH", "valueDensity": "NOT_DEFINED", "vectorString": "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "NONE", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "published": "2025-12-31T19:15:43.923", "references": [{"url": "https://github.com/obgm/libcoap/commit/30db3ea", "tags": ["Patch"], "source": "disclosure@vulncheck.com"}, {"url": "https://github.com/obgm/libcoap/pull/1737", "tags": ["Issue Tracking"], "source": "disclosure@vulncheck.com"}, {"url": "https://libcoap.net/", "tags": ["Product"], "source": "disclosure@vulncheck.com"}, {"url": "https://www.vulncheck.com/advisories/libcoap-stack-based-buffer-overflow-in-address-resolution-dos-or-potential-rce", "tags": ["Third Party Advisory"], "source": "disclosure@vulncheck.com"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "disclosure@vulncheck.com", "description": [{"lang": "en", "value": "CWE-121"}]}, {"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "CWE-787"}]}], "descriptions": [{"lang": "en", "value": "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)."}], "lastModified": "2026-01-14T20:18:32.890", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:libcoap:libcoap:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "22875932-4B0B-490A-AE0E-751EBC7CD54A", "versionEndIncluding": "4.3.5"}], "operator": "OR"}]}], "sourceIdentifier": "disclosure@vulncheck.com"}