Vulnerability · Published Oct 20, 2026 · Assigned by VulnCheck

CVE-2026-113583Cypht 2.0.0 through 2.12.2 Stored DOM XSS via externalResources.js

Medium 6.1

In plain English

A medium-severity cross-site scripting in cypht from cypht-org. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 33% of all known vulnerabilities).

Severity (CVSS 3.1)6.1Medium

Exploit odds (30 days)0.4%top 66.8% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

Cypht webmail 2.0.0 through 2.12.2 contains a DOM-based cross-site scripting vulnerability that allows remote attackers to execute arbitrary JavaScript by crafting malicious alt text or URL values in an HTML email's external image tag when ALLOW_EXTERNAL_IMAGE_SOURCES is enabled. Attackers can send a specially crafted email so that when the victim opens it, the externalResources.js code builds the blocked-image notice using innerHTML with decoded email-derived values, triggering script execution in the victim's authenticated session to read mailboxes, send email, or change settings.

Affected products (as reported)

Vendor	Product	Versions
cypht-org	cypht	2.0.0 – before 2.13.0

Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

References

https://github.com/cypht-org/cypht/pull/2118/changes/75d2fb83d228be2aaa37036a11eea68d82122d85 issue-tracking, patch
Vendor Patch patch
VulnCheck Advisory: Cypht 2.0.0 through 2.12.2 Stored DOM XSS via externalResources.js third-party-advisory