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7.5
HIGH CVSS 3.1
CVE-2026-23845
Mailpit Vulnerable to Server-Side Request Forgery (SSRF) via HTML Check API
Description

Mailpit is an email testing tool and API for developers. Versions prior to 1.28.3 are vulnerable to Server-Side Request Forgery (SSRF) via HTML Check CSS Download. The HTML Check feature (`/api/v1/message/{ID}/html-check`) is designed to analyze HTML emails for compatibility. During this process, the `inlineRemoteCSS()` function automatically downloads CSS files from external `<link rel="stylesheet" href="...">` tags to inline them for testing. Version 1.28.3 fixes the issue.

INFO

Published Date :

Jan. 19, 2026, 7:16 p.m.

Last Modified :

Feb. 5, 2026, 6:35 p.m.

Remotely Exploit :

Yes !

Source :

[email protected]
Affected Products

The following products are affected by CVE-2026-23845 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Axllent mailpit
: Total Affected Vendor : 1 | Products : 1
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 3.1 MEDIUM [email protected]
CVSS 3.1 HIGH [email protected]
Solution
Update Mailpit to version 1.28.3 or later to fix the SSRF vulnerability.
  • Update Mailpit to version 1.28.3 or later.
  • Review and update relevant configurations.
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2026-23845.

URL Resource
https://github.com/axllent/mailpit/commit/1679a0aba592ebc8487a996d37fea8318c984dfe Patch
https://github.com/axllent/mailpit/releases/tag/v1.28.3 Product Release Notes
https://github.com/axllent/mailpit/security/advisories/GHSA-6jxm-fv7w-rw5j Exploit Vendor Advisory
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-23845 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-23845 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-23845 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2026-23845 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • Initial Analysis by [email protected]

    Feb. 05, 2026

    Action Type Old Value New Value
    Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
    Added CPE Configuration OR *cpe:2.3:a:axllent:mailpit:*:*:*:*:*:*:*:* versions up to (excluding) 1.28.3
    Added Reference Type GitHub, Inc.: https://github.com/axllent/mailpit/commit/1679a0aba592ebc8487a996d37fea8318c984dfe Types: Patch
    Added Reference Type GitHub, Inc.: https://github.com/axllent/mailpit/releases/tag/v1.28.3 Types: Product, Release Notes
    Added Reference Type GitHub, Inc.: https://github.com/axllent/mailpit/security/advisories/GHSA-6jxm-fv7w-rw5j Types: Exploit, Vendor Advisory
  • New CVE Received by [email protected]

    Jan. 19, 2026

    Action Type Old Value New Value
    Added Description Mailpit is an email testing tool and API for developers. Versions prior to 1.28.3 are vulnerable to Server-Side Request Forgery (SSRF) via HTML Check CSS Download. The HTML Check feature (`/api/v1/message/{ID}/html-check`) is designed to analyze HTML emails for compatibility. During this process, the `inlineRemoteCSS()` function automatically downloads CSS files from external `<link rel="stylesheet" href="...">` tags to inline them for testing. Version 1.28.3 fixes the issue.
    Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N
    Added CWE CWE-918
    Added Reference https://github.com/axllent/mailpit/commit/1679a0aba592ebc8487a996d37fea8318c984dfe
    Added Reference https://github.com/axllent/mailpit/releases/tag/v1.28.3
    Added Reference https://github.com/axllent/mailpit/security/advisories/GHSA-6jxm-fv7w-rw5j
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
Base CVSS Score: 7.5
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact