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Libcoap CVE-2025-59391

| EUVDEUVD-2025-201786 MEDIUM
Out-of-bounds Read (CWE-125)
2025-12-08 cve@mitre.org
6.5
CVSS 3.1 · NVD
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Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, read limits
MITRE ATT&CK

1 technique across 1 tactic: Collection

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

Out-of-bounds reads can leak sensitive information from memory, while out-of-bounds writes can corrupt data or enable code execution. With a CVSS score of 6.5 (MEDIUM), this represents a moderate risk.

Exploit ScenarioDerived

An attacker provides a crafted input that causes the application to read or write beyond buffer boundaries, potentially leaking memory contents or hijacking control flow.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 15, 2026

A memory disclosure vulnerability exists in libcoap's OSCORE configuration parser in libcoap before release-4.3.5-patches. An out-of-bounds read may occur when parsing certain configuration values, allowing an attacker to infer or read memory beyond string boundaries in the .rodata section. This could potentially lead to information disclosure or denial of service.

Earlier versions of this analysis (1)
v1 Mar 15, 2026 - 17:54 CVSS 6.5

RemediationAI

A vendor patch is available — apply it immediately. Implement proper bounds checking on all array and buffer accesses. Use memory-safe languages or static analysis tools to detect OOB issues.

Affected VersionsENISA

n/a n/a

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

An out-of-bounds memory access occurs when code reads from or writes to memory locations outside the intended buffer boundaries. This vulnerability is classified as Out-of-bounds Read (CWE-125).

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 6.5 MEDIUM
AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
SUSE MEDIUM

Primary rating from NVD.

CVSS VectorNVD

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

Lifecycle Timeline

2
Patch released
Mar 15, 2026 - 17:54 nvd
Patch available
CVE Published
Dec 08, 2025 - 17:16 nvd
MEDIUM 6.5

Executive ViewAI

Why It Matters

Organizations using libcoap should be aware of notable risk from CVE-2025-59391, a out-of-bounds read vulnerability rated CVSS 6.5. Exploitation could cause memory corruption or application crashes. A patch is available and should be applied during regular vulnerability management.

Business Impact: Moderate
Compensating Controls

Apply vendor patch. If patching is delayed: enable ASLR/DEP, apply network segmentation.

Threat Intelligence Overview

EPSS Score
0.1%
Top 83% exploitable
Data Quality
5 sources
Confidence: Medium

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.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.1%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
Yes

Priority Score

32
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +32
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

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.

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

CVE-2024-0962 HIGH POC
7.8 Jan 27

A vulnerability was found in obgm libcoap 4.3.4. Rated high severity (CVSS 7.8), this vulnerability is low attack comple

CVE-2024-31031 HIGH POC
7.5 Apr 17

An issue in `coap_pdu.c` in libcoap 4.3.4 allows attackers to cause undefined behavior via a sequence of messages leadin

CVE-2023-30362 HIGH POC
7.5 Jun 23

Buffer Overflow vulnerability in coap_send function in libcoap library 4.3.1-103-g52cfd56 fixed in 4.3.1-120-ge242200 al

CVE-2023-35862 MEDIUM POC
6.5 Jun 19

libcoap 4.3.1 contains a buffer over-read via the function coap_parse_oscore_conf_mem at coap_oscore.c. Rated medium sev

CVE-2026-29013 HIGH
8.8 Apr 17

Out-of-bounds read in libcoap's OSCORE CBOR parsing can escalate to heap buffer overflow, enabling remote unauthenticate

CVE-2025-34468 HIGH
8.2 Dec 31

Availability loss and potential remote code execution in libcoap (versions up to and including 4.3.5, before commit 30db

CVE-2025-65501 MEDIUM
4.3 Nov 24

Null pointer dereference in coap_dtls_info_callback() in OISM libcoap 4.3.5 allows remote attackers to cause a denial of

CVE-2025-65500 MEDIUM
4.3 Nov 24

NULL pointer dereference in coap_dtls_generate_cookie() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attack

CVE-2025-65499 MEDIUM
4.3 Nov 24

Array index error in tls_verify_call_back() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attackers to cause

CVE-2025-65498 MEDIUM
4.3 Nov 24

NULL pointer dereference in coap_dtls_generate_cookie() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attack

CVE-2025-65497 MEDIUM
4.3 Nov 24

NULL pointer dereference in coap_dtls_generate_cookie() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attack

CVE-2025-65496 MEDIUM
4.3 Nov 24

NULL pointer dereference in coap_dtls_generate_cookie() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attack

Vendor StatusVendor

SUSE

Severity: Medium

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