CVE-2025-65499Network attack vector

DTLS endpoint crash via unchecked array index

Published Nov 24, 2025 · Updated Nov 24, 2025

An array index error in libcoap 4.3.5 allows remote attackers to crash a DTLS endpoint through a crafted certificate handshake. The tls_verify_call_back() function passes the unchecked -1 result of SSL_get_ex_data_X509_STORE_CTX_idx() to X509_STORE_CTX_get_ex_data(), causing a null-pointer read. The OpenSSL-backed certificate-verification path must process the handshake; the resulting segmentation fault interrupts the affected client or server process.

CVSS severity4.3
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

An array index error in libcoap 4.3.5 allows remote attackers to crash a DTLS endpoint through a crafted certificate handshake. The tls_verify_call_back() function passes the unchecked -1 result of SSL_get_ex_data_X509_STORE_CTX_idx() to X509_STORE_CTX_get_ex_data(), causing a null-pointer read. The OpenSSL-backed certificate-verification path must process the handshake; the resulting segmentation fault interrupts the affected client or server process.

The record

CVE
CVE-2025-65499
Published
Nov 24, 2025
Updated
Nov 24, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-129, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 24, 2025CVE publishedPublication date reported by the CVE source.
  2. Nov 24, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.3CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-129Improper Validation of Array Index
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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