PuTTY TELNET Proxy Authentication Trust Misuse

Publication date: 2026-05-25

Last updated on: 2026-05-27

Assigner: MITRE

Description

PuTTY 0.77 before 0.84 uses a copy of the PuTTY icon as a trust indication for TELNET data but the trust status is not cleared between proxy authentication and the main session.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-05-25

Last Modified

2026-05-27

Generated

2026-07-06

AI Q&A

2026-05-26

EPSS Evaluated

2026-07-04

NVD

CVE-2026-48851

EUVD

EUVD-2026-31731

Affected Vendors & Products

Vendor	Product	Version / Range
putty	putty	From 0.77 (inc) to 0.84 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-451	The user interface (UI) does not properly represent critical information to the user, allowing the information - or its source - to be obscured or spoofed. This is often a component in phishing attacks.

Attack-Flow Graph

Executive Summary

This vulnerability exists in PuTTY versions 0.77 before 0.84. PuTTY uses a copy of its icon as a trust indication for TELNET data. However, the trust status represented by this icon is not cleared between proxy authentication and the main session, which can lead to incorrect trust assumptions.

Impact Analysis

Because the trust status is not properly cleared between proxy authentication and the main session, users or systems might mistakenly trust TELNET data that should not be trusted. This could potentially lead to security issues such as accepting malicious data or unauthorized access during the session.

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