Bug 2426524 (CVE-2025-34468)

Summary: CVE-2025-34468 libcoap: libcoap: Remote code execution or Denial of Service via stack-based buffer overflow in address resolution
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in libcoap. A remote attacker can exploit a stack-based buffer overflow vulnerability in the address resolution function. This occurs when attacker-controlled hostname data is copied into a fixed-size buffer without proper validation. This can lead to a crash, resulting in a Denial of Service (DoS), and depending on system configurations, could potentially enable remote code execution. Exploitation requires the proxy logic to be enabled in an application using libcoap.
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Bug Depends On: 2426602, 2426603    
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Description OSIDB Bzimport 2025-12-31 19:03:08 UTC 
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).