CVE-2025-34468Network attack vectorHinoki check available

Crash or code execution via unchecked hostname copy

Published Dec 31, 2025 · Updated Dec 31, 2025

Stack-based buffer overflow in libcoap 4.3.5 and earlier allows remote attackers to crash proxy-enabled applications via a crafted hostname. coap_resolve_address_info() copies address->length bytes into the fixed 256-byte addrstr stack buffer without first rejecting oversized hostnames. The proxy request path must be enabled; memory protections and compiler options determine whether corruption stops at a crash or permits code execution.

CVSS severity8.2
High
EPSS probability0.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Stack-based buffer overflow in libcoap 4.3.5 and earlier allows remote attackers to crash proxy-enabled applications via a crafted hostname. coap_resolve_address_info() copies address->length bytes into the fixed 256-byte addrstr stack buffer without first rejecting oversized hostnames. The proxy request path must be enabled; memory protections and compiler options determine whether corruption stops at a crash or permits code execution.

The record

CVE
CVE-2025-34468
Published
Dec 31, 2025
Updated
Dec 31, 2025
Vendor
libcoap
Product
libcoap
Classifications
CWE-787, CWE-121, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 31, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 31, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=4.3.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

libcoap · libcoapversion=0 <=4.3.5

Published CVSS scores

9.8NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.2VulnCheckCVSS: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 describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
CWE-121Stack-based Buffer Overflow
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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