What is the CVSS score of CVE-2026-23845?

CVE-2026-23845 has a CVSS 3.1 base score of 5.8 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N. EPSS exploitation probability: 0.1%.

Is there a public PoC exploit available for CVE-2026-23845?

Yes, a public proof-of-concept exploit is available for CVE-2026-23845. Prioritise patching immediately. EPSS: 0.1%.

How to fix or mitigate CVE-2026-23845?

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Vendor patch is available.

Mailpit CVE-2026-23845

MEDIUM

Server-Side Request Forgery (SSRF) (CWE-918)

2026-01-19 security-advisories@github.com

GHSA-6jxm-fv7w-rw5j

SSRF Mailpit Suse Axllent

5.8

CVSS 3.1 · GitHub Advisory

View

Vulnerability Assessment

Weakness	CWE CWE-918 OWASP Top 10:2025 A01:2025 - Broken Access Control ASVS 5.0 V4 - API and Web Service URL allowlisting, SSRF prevention MITRE ATT&CK 2 techniques across 2 tactics: Initial Access, Credential Access The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Impact	CVSS 5.8 (MEDIUM). Attack vector: Network. Complexity: Low. Privileges required: None. User interaction: None. Exploitable via remote/network. Public exploit/POC available.
Exploit ScenarioDerived	A remote attacker could exploit this vulnerability to compromise the affected system.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).

Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Mailpit versions before 1.28.3 contain a server-side request forgery vulnerability in the HTML Check feature that allows unauthenticated attackers to trigger arbitrary HTTP requests by crafting malicious CSS links in email messages. The vulnerability exists in the CSS inlining function which automatically downloads external stylesheets without proper validation. Public exploit code exists for this issue, though a patch is available in version 1.28.3 and later.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 21:54 CVSS 5.8

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. [CVSS 5.8 MEDIUM]

RemediationAI

A vendor patch is available — apply it immediately. Restrict network access to the affected service where possible.

Affected Packages

go github.com/axllent/mailpit fix: 1.28.3

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in go

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Classified as CWE-918 (Server-Side Request Forgery (SSRF)). Affects Mailpit. 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.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

GitHub Advisory PRIMARY 5.8 MEDIUM

AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N

SUSE MEDIUM

Primary rating from GitHub Advisory.

CVSS VectorGitHub Advisory

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

Low

Integrity

None

Availability

None

Lifecycle Timeline

PoC Detected

Feb 05, 2026 - 18:35 vuln.today

Public exploit code

Patch released

Feb 05, 2026 - 18:35 nvd

Patch available

CVE Published

Jan 19, 2026 - 19:16 nvd

MEDIUM 5.8

DescriptionGitHub Advisory

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.

Executive ViewAI

Why It Matters

Organizations using Mailpit should be aware of moderate risk from CVE-2026-23845, a server-side request forgery vulnerability rated CVSS 5.8. Users could be tricked into performing unintended actions. Proof-of-concept code is publicly available. A patch is available and should be applied during regular vulnerability management.

Business Impact: Low

Compensating Controls

Apply vendor patch. If patching is delayed: implement egress filtering, block metadata endpoints.

Threat Intelligence Overview

EPSS Score

0.1%

Top 82% exploitable

Exploit

POC

Public exploit code exists

Data Quality

4 sources

Confidence: Medium

NVD

CVE.org

EPSS Vendor

GitHub

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity MEDIUM

CISA KEV No

Public POC Yes

EPSS 0.1%

Patch available Yes

Active threat No

Deciding rule

MEDIUM severity (CVSS 4.0-6.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

Poc

System Exposure· derived

Open

Automatable· derived

Yes

Human Impact

Low

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +29

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Server-Side Request Forgery HIGH

Server-Side Request Forgery exploits applications that fetch remote resources based on user-supplied URLs.

Affected Products (CPE)GitHub Advisory

cpe:2.3:a:axllent:mailpit:*:*:*:*:*:*:*:*

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Vendor StatusVendor

SUSE

Severity: Medium

Product	Status
openSUSE Leap 15.6	Fixed
SUSE Linux Enterprise Module for Package Hub 15 SP5	Fixed
SUSE Linux Enterprise Module for Package Hub 15 SP6	Fixed
openSUSE Leap 15.5	Fixed

References

Advisories & patches

PATCH https://github.com/axllent/mailpit/commit/1679a0aba592ebc8487a996d37fea8318c984dfe ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:0403/ REF https://github.com/axllent/mailpit/releases/tag/v1.28.3

Search Externally

GitHub PoC

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