CVE-2026-113583: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in cypht-org cypht
Description
Cypht webmail versions 2.0.0 through 2.12.2 have a DOM-based cross-site scripting (XSS) vulnerability. This flaw allows remote attackers to execute arbitrary JavaScript by sending specially crafted emails containing malicious alt text or URL values in external image tags when the ALLOW_EXTERNAL_IMAGE_SOURCES setting is enabled. The vulnerability arises because externalResources.js uses innerHTML with decoded email-derived values to build the blocked-image notice, enabling script execution in the victim's authenticated session.
CVSS v4.0
Score 5.3medium
Affected software
cypht-org
cypht
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-113583 describes a DOM-based cross-site scripting vulnerability in cypht-org's cypht webmail software versions 2.0.0 through 2.12.2. When the ALLOW_EXTERNAL_IMAGE_SOURCES feature is enabled, an attacker can craft an HTML email with malicious alt text or URL attributes in external image tags. Upon the victim opening the email, the externalResources.js script constructs a blocked-image notice using innerHTML with untrusted, decoded email content, leading to arbitrary JavaScript execution within the victim's authenticated session. This can allow attackers to read mailboxes, send emails, or modify settings.
Potential Impact
Successful exploitation allows remote attackers to execute arbitrary JavaScript in the context of the victim's authenticated session. This can lead to unauthorized mailbox access, sending emails on behalf of the user, or changing user settings. The vulnerability requires user interaction (opening the crafted email) and the ALLOW_EXTERNAL_IMAGE_SOURCES setting to be enabled.
Mitigation Recommendations
No official patch or fix information is provided in the available data. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, consider disabling the ALLOW_EXTERNAL_IMAGE_SOURCES setting to prevent exploitation of this vulnerability.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-10-20T11:32:02.400Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6ad755342cdf04f65626c80b
Added to database: 10/20/2026, 11:49:08 UTC
Last enriched: 10/20/2026, 12:03:16 UTC
Last updated: 10/20/2026, 12:04:05 UTC
Views: 5
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