CVE-2026-49864: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in butlerx wetty
wetty provides terminal access in browser over http/https. Prior to version 3.0.4, the wetty client decodes a base64 filename from the file-download escape sequence and interpolates it raw into a Toastify HTML string (`escapeMarkup: false`). Any output the victim renders - a `cat`'d file, a tailed log, an SSH MOTD, a `curl` response - that contains `\x1b[5i...:...\x1b[4i` runs script in the wetty origin and types attacker-chosen keystrokes into the victim's SSH session. Version 3.0.4 fixes the issue.
AI Analysis
Technical Summary
The wetty client before version 3.0.4 improperly neutralizes input during web page generation by decoding a base64 filename from a file-download escape sequence and interpolating it raw into a Toastify HTML string with escapeMarkup set to false. This allows an attacker to craft input containing specific escape sequences (`\x1b[5i...:...\x1b[4i`) that execute scripts in the wetty origin context and simulate keystrokes in the victim's SSH session. The vulnerability is identified as CWE-79 (Improper Neutralization of Input During Web Page Generation). Version 3.0.4 addresses this issue.
Potential Impact
Successful exploitation allows an attacker to execute arbitrary scripts within the wetty web client origin and inject keystrokes into the victim's SSH session, potentially leading to unauthorized command execution or session manipulation. This compromises the confidentiality and integrity of the victim's terminal session.
Mitigation Recommendations
Upgrade wetty to version 3.0.4 or later, where this vulnerability is fixed. No other official remediation or temporary fixes are documented. Patch status is not explicitly confirmed in the vendor advisory, but the version 3.0.4 release addresses the issue.
CVE-2026-49864: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in butlerx wetty
Description
wetty provides terminal access in browser over http/https. Prior to version 3.0.4, the wetty client decodes a base64 filename from the file-download escape sequence and interpolates it raw into a Toastify HTML string (`escapeMarkup: false`). Any output the victim renders - a `cat`'d file, a tailed log, an SSH MOTD, a `curl` response - that contains `\x1b[5i...:...\x1b[4i` runs script in the wetty origin and types attacker-chosen keystrokes into the victim's SSH session. Version 3.0.4 fixes the issue.
CVSS v4.0
Score 8.6high
Affected software
butlerx
wetty
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The wetty client before version 3.0.4 improperly neutralizes input during web page generation by decoding a base64 filename from a file-download escape sequence and interpolating it raw into a Toastify HTML string with escapeMarkup set to false. This allows an attacker to craft input containing specific escape sequences (`\x1b[5i...:...\x1b[4i`) that execute scripts in the wetty origin context and simulate keystrokes in the victim's SSH session. The vulnerability is identified as CWE-79 (Improper Neutralization of Input During Web Page Generation). Version 3.0.4 addresses this issue.
Potential Impact
Successful exploitation allows an attacker to execute arbitrary scripts within the wetty web client origin and inject keystrokes into the victim's SSH session, potentially leading to unauthorized command execution or session manipulation. This compromises the confidentiality and integrity of the victim's terminal session.
Mitigation Recommendations
Upgrade wetty to version 3.0.4 or later, where this vulnerability is fixed. No other official remediation or temporary fixes are documented. Patch status is not explicitly confirmed in the vendor advisory, but the version 3.0.4 release addresses the issue.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-01T22:03:19.640Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a7e1a7fbf8831d539b180dd
Added to database: 08/13/2026, 19:26:55 UTC
Last enriched: 08/21/2026, 13:04:37 UTC
Last updated: 09/27/2026, 05:12:49 UTC
Views: 50
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