Libcoap vulnerabilities
We track 9 vulnerabilities in Libcoap products. 9 are rated high or critical, and none are known to be exploited. The most recent was published on April 17, 2026.
Latest Libcoap vulnerabilities
- 9.8 Critical severity
libcoap: Out-of-bounds Read
libcoap contains out-of-bounds read vulnerabilities in OSCORE Appendix B.2 CBOR unwrap handling where get_byte_inc() in src/oscore/oscore_cbor.c relies solely on assert() for bounds checking, which is removed in release builds compiled with NDEBUG. Attackers c
- 9.8 Critical severity
libcoap: Out-of-bounds Write
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 attack
- 7.5 High severity
Libcoap: Signed to Unsigned Conversion Error
Integer signedness 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 TLS certificate that causes i2d_X509() to return -1 and be misused as a malloc() size parameter.
- 7.5 High severity
Libcoap: NULL Pointer Dereference
NULL pointer dereference in get_san_or_cn_from_cert() in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attackers to cause a denial of service via a crafted X.509 certificate that causes sk_GENERAL_NAME_value() to return NULL.
- 7.5 High severity
Libcoap: NULL Pointer Dereference
NULL pointer dereference in src/coap_openssl.c in OISM libcoap 4.3.5 allows remote attackers to cause a denial of service via a crafted DTLS/TLS connection that triggers BIO_get_data() to return NULL.
- 7.5 High severity
libcoap: Buffer Copy without Checking Size of Input
A NULL pointer dereference in libcoap v4.3.5-rc2 and below allows a remote attacker to cause a denial of service via the coap_handle_request_put_block function in src/coap_block.c.
- 7.5 High severity
libcoap: Uncontrolled Resource Consumption
An issue in obgm and Libcoap v.a3ed466 allows a remote attacker to cause a denial of service via thecoap_context_t function in the src/coap_threadsafe.c:297:3 component.
- 7.5 High severity
libcoap: Integer Overflow or Wraparound
An issue in `coap_pdu.c` in libcoap 4.3.4 allows attackers to cause undefined behavior via a sequence of messages leading to unsigned integer overflow.
- 7.5 High severity
Libcoap: Out-of-bounds Read
Buffer Overflow vulnerability in coap_send function in libcoap library 4.3.1-103-g52cfd56 fixed in 4.3.1-120-ge242200 allows attackers to obtain sensitive information via malformed pdu.