CVE-2025-65495
Integer signedness error in tls_verify_call_back() in src/coap_openssl.c in OISM libcoap 4.3.5...
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
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.
- Record
CVE-2025-65495- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-195
- Updated
- 2026-11-02
EUVDEUVD-2025-198714
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.
- Record
EUVD-2025-198714- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-vr3h-29qc-jvjf
Integer signedness error in tls_verify_call_back() in src/coap_openssl.c in OISM libcoap 4.3.5...
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.
- Record
GHSA-vr3h-29qc-jvjf- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-195
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2025-65495- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-195
- Updated
- 2026-11-05
OSV
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.
- Record
CVE-2025-65495- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-07
OSVDEBIAN-CVE-2025-65495
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.
- Record
DEBIAN-CVE-2025-65495- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2025-65495
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.
- Record
UBUNTU-CVE-2025-65495- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVopenSUSE-SU-2025:15780-1 No score
libcoap-devel-4.3.5a-1.1 on GA media
These are all security issues fixed in the libcoap-devel-4.3.5a-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2025:15780-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
libcoap3Debian:12 |
All versions, plus listed versions 4.3.1-14.3.1-24.3.3-14.3.4-14.3.4-1.1 Show 5 moreShow less4.3.4-1.1~exp14.3.5-14.3.5-24.3.5-34.3.5-4 |
None known |
libcoap3Debian:13 |
before 4.3.4-1.1+deb13u2, plus listed versions 4.3.4-1.14.3.4-1.1+deb13u1 |
4.3.4-1.1+deb13u2 |
libcoap3Debian:14 |
before 4.3.5-2, plus listed versions 4.3.4-1.14.3.5-1 |
4.3.5-2 |
libcoapUbuntu:18.04:LTS |
All versions, plus listed versions 4.1.2-1 |
None known |
libcoap2Ubuntu:20.04:LTS |
All versions, plus listed versions 4.2.0-24.2.1-1 |
None known |
libcoap2Ubuntu:22.04:LTS |
All versions, plus listed versions 4.2.1-14.2.1-1build1 |
None known |
libcoap3Ubuntu:22.04:LTS |
All versions, plus listed versions 4.3.0-24.3.0-2build1 |
None known |
libcoap3Ubuntu:24.04:LTS |
All versions, plus listed versions 4.3.1-24.3.3-14.3.4-14.3.4-1.1build24.3.4-1.1build34.3.4-1.1build4 |
None known |
libcoap3Ubuntu:25.10 |
All versions, plus listed versions 4.3.4-1.1build4 |
None known |
libcoap3Ubuntu:26.10 |
All versions, plus listed versions 4.3.5-24.3.5-34.3.5-44.3.5-4ubuntu1 |
None known |
libcoap3Ubuntu:26.04:LTS |
All versions, plus listed versions 4.3.4-1.1build44.3.5-14.3.5-2 |
None known |
libcoapopenSUSE:Tumbleweed From an advisory covering 9 CVEs |
before 4.3.5a-1.1 | 4.3.5a-1.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected | ||
| facts | NVD | |
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2025-65495 is a high vulnerability (CVSS 7.5) in Libcoap, published November 24, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.26%, the 17th percentile. Fixed in libcoap3 4.3.4-1.1+deb13u2.
References
github.com/obgm/libcoap/issues/1744
nvd.nist.gov/vuln/detail/CVE-2025-65495
security-tracker.debian.org/tracker/CVE-2025-65495
Show 11 moreShow less
ubuntu.com/security/CVE-2025-65495
cve.org/CVERecord?id=CVE-2025-65495
suse.com/security/cve/CVE-2025-65493