CVE-2025-34468
libcoap Stack-Based Buffer Overflow in Address Resolution DoS or Potential RCE
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).
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
8.2
libcoap Stack-Based Buffer Overflow in Address Resolution DoS or Potential RCE
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).
- Record
CVE-2025-34468- CVSS 4.0
- 8.2 High
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N - Weakness
- CWE-121
- Updated
- 2026-11-08
EUVDEUVD-2025-206064
8.2
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).
- Record
EUVD-2025-206064- CVSS 4.0
- 8.2 High
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N - Updated
- 2026-11-08
GitHub AdvisoriesGHSA-rj9f-6c28-qf6x
8.2
libcoap versions up to and including 4.3.5, prior to commit 30db3ea, contain a stack-based buffer...
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).
- Record
GHSA-rj9f-6c28-qf6x- CVSS 4.0
- 8.2 High
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-121, CWE-787
- Updated
- 2026-11-02
NVD
8.2
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).
- Record
CVE-2025-34468- CVSS 4.0
- 8.2 High
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-121, CWE-787
- Updated
- 2026-11-02
OSV
8.2
libcoap Stack-Based Buffer Overflow in Address Resolution DoS or Potential RCE
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).
- Record
CVE-2025-34468- CVSS 4.0
- 8.2 High
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N - Weakness
- CWE-121
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2025-34468
9.8
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).
- Record
DEBIAN-CVE-2025-34468- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2025-34468
8.2
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).
- Record
UBUNTU-CVE-2025-34468- CVSS 4.0
- 8.2 High
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N - CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - 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+deb13u3, plus listed versions 4.3.4-1.14.3.4-1.1+deb13u14.3.4-1.1+deb13u2 |
4.3.4-1.1+deb13u3 |
libcoap3Debian:14 |
before 4.3.5-3, plus listed versions 4.3.4-1.14.3.5-14.3.5-2 |
4.3.5-3 |
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 |
History
| Recorded | Changed | Sources |
|---|---|---|
| facts, references | CVE List | |
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2025-34468 is a high vulnerability (CVSS 8.2) in Libcoap, published December 31, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.75%, the 55th percentile. Fixed in libcoap3 4.3.4-1.1+deb13u3.