CVE-2025-65500

Published Nov 24, 2025

Last updated 4 months ago

CVSS medium 4.3

Overview

Description
NULL pointer dereference in coap_dtls_generate_cookie() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attackers to cause a denial of service via a crafted DTLS handshake that triggers SSL_get_SSL_CTX() to return NULL.
Source
cve@mitre.org
NVD status
Analyzed
Products
libcoap

Risk scores

CVSS 3.1

Type
Secondary
Base score
4.3
Impact score
1.4
Exploitability score
2.8
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
Severity
MEDIUM

Weaknesses

134c704f-9b21-4f2e-91b3-4a467353bcc0
CWE-476

Social media

Hype score
Not currently trending

  1. CVE-2025-65500 NULL pointer dereference in coap_dtls_generate_cookie() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attackers to cause a denial of service via a crafted… https://t.co/AR4DEwUMXb

    @CVEnew

    24 Nov 2025

    183 Impressions

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Configurations

Related CVEs

  1. 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).•CVE-2025-34468
  2. 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.•CVE-2025-59391
  3. NULL pointer dereference in coap_dtls_generate_cookie() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attackers to cause a denial of service via a crafted DTLS handshake that triggers SSL_get_SSL_CTX() to return NULL.•CVE-2025-65496
  4. NULL pointer dereference in coap_dtls_generate_cookie() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attackers to cause a denial of service via a crafted DTLS handshake that triggers SSL_get_SSL_CTX() to return NULL.•CVE-2025-65498
  5. Array index error in tls_verify_call_back() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attackers to cause a denial of service via a crafted DTLS handshake that triggers SSL_get_ex_data_X509_STORE_CTX_idx() to return -1.•CVE-2025-65499

References

Sources include official advisories and independent security research.