CVE-2025-34451Public exploit

Local process crash via oversized HTTP proxy credentials

Published Dec 18, 2025 · Updated Dec 18, 2025

Stack-based buffer overflow in proxy_from_string() in proxychains-ng 4.17 and earlier allows local users to crash a wrapped process. The HTTP-proxy parser applies its 255-byte credential-length check only to SOCKS5 entries, then copies oversized usernames or passwords into 256-byte stack buffers. Exploitation requires a crafted proxy configuration to be loaded; the demonstrated consequence is process termination, while code execution has not been established.

CVSS severity6.9
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in proxy_from_string() in proxychains-ng 4.17 and earlier allows local users to crash a wrapped process. The HTTP-proxy parser applies its 255-byte credential-length check only to SOCKS5 entries, then copies oversized usernames or passwords into 256-byte stack buffers. Exploitation requires a crafted proxy configuration to be loaded; the demonstrated consequence is process termination, while code execution has not been established.

The record

CVE
CVE-2025-34451
Published
Dec 18, 2025
Updated
Dec 18, 2025
Vendor
rofl0r
Product
proxychains-ng
Classifications
CWE-121, CWE-787, T1499.004
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 18, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 18, 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 <=4.17

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

rofl0r · proxychains-ngversion=0 <=4.17

Published CVSS scores

6.9VulnCheckCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
7.8NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-121Stack-based Buffer Overflow
CWE-787Out-of-bounds Write
T1499.004Application or System Exploitation

Public exploit references

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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