CVE-2025-34468

libcoap3: libcoap versions up to and including 4.3.5, prior to commit 30db3ea, contain a stack-based buffer overflow in address...

CVE-2025-34468 is fixed in 8 products on 1 platform, first by DEBIAN-CVE-2025-34468, released December 31, 2025. It is not reported as exploited. Patch Radar priority: Urgent.

Urgent
CVSS
9.8
critical
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0075
55th percentile

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).

Where it's fixed

ProductFixed inFixReleased
Linux
libcoap · Fedora 43 4.3.5b-1.fc43 FEDORA-2026-0CE923A09D Apr 17, 2026
libcoap-debuginfo · Fedora 43 4.3.5b-1.fc43 FEDORA-2026-0CE923A09D Apr 17, 2026
libcoap-debugsource · Fedora 43 4.3.5b-1.fc43 FEDORA-2026-0CE923A09D Apr 17, 2026
libcoap-devel · Fedora 43 4.3.5b-1.fc43 FEDORA-2026-0CE923A09D Apr 17, 2026
libcoap-doc · Fedora 43 4.3.5b-1.fc43 FEDORA-2026-0CE923A09D Apr 17, 2026
libcoap-utils · Fedora 43 4.3.5b-1.fc43 FEDORA-2026-0CE923A09D Apr 17, 2026
libcoap-utils-debuginfo · Fedora 43 4.3.5b-1.fc43 FEDORA-2026-0CE923A09D Apr 17, 2026
libcoap3 · Debian 13.5 (trixie) 4.3.4-1.1+deb13u3 DEBIAN-CVE-2025-34468 Dec 31, 2025
libcoap3 · Debian 14 4.3.5-3 DEBIAN-CVE-2025-34468 Dec 31, 2025

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