How severe is GHSA-524m-q5m7-79mm?

GHSA-524m-q5m7-79mm has a CVSS score of 6.5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by GHSA-524m-q5m7-79mm?

GHSA-524m-q5m7-79mm affects the following packages: github.com/axllent/mailpit (Go), github.com/axllent/mailpit (Go). Ecosystems affected: Go.

How do I fix GHSA-524m-q5m7-79mm?

Update github.com/axllent/mailpit to 1.28.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-524m-q5m7-79mm is resolved across your whole dependency graph.

How do I detect GHSA-524m-q5m7-79mm in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/axllent/mailpit. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-524m-q5m7-79mm if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-524m-q5m7-79mm?

O3 pinpoints whether GHSA-524m-q5m7-79mm is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-524m-q5m7-79mm actively exploited in the wild?

No public exploit code has been indexed for GHSA-524m-q5m7-79mm yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-524m-q5m7-79mm?

GHSA-524m-q5m7-79mm has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 11th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-524m-q5m7-79mm?

GHSA-524m-q5m7-79mm is classified as CWE-1385 (CWE-1385). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-524m-q5m7-79mm published, and has it been updated?

GHSA-524m-q5m7-79mm was published on January 13, 2026 and was last updated on February 3, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹 Go

GHSA-524m-q5m7-79mm

MEDIUM

Mailpit is vulnerable to Cross-Site WebSocket Hijacking (CSWSH) allowing unauthenticated access to emails

Also known asCVE-2026-22689GO-2026-4310

Published

Jan 13, 2026

Updated

Feb 3, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk11th percentile+0.20%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

2 pkgs affected

🐹github.com/axllent/mailpit🐹github.com/axllent/mailpit

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Summary The Mailpit WebSocket server is configured to accept connections from any origin. This lack of Origin header validation introduces a Cross-Site WebSocket Hijacking (CSWSH) vulnerability.

An attacker can host a malicious website that, when visited by a developer running Mailpit locally, establishes a WebSocket connection to the victim's Mailpit instance (default ws://localhost:8025). This allows the attacker to intercept sensitive data such as email contents, headers, and server statistics in real-time.

Vulnerable Code The vulnerability exists in server/websockets/client.go where the CheckOrigin function is explicitly set to return true for all requests, bypassing standard Same-Origin Policy (SOP) protections provided by the gorilla/websocket library.

https://github.com/axllent/mailpit/blob/877a9159ceeaf380d5bb0e1d84017b24d2e7b361/server/websockets/client.go#L34-L39

Impact This vulnerability impacts the Confidentiality of the data stored in or processed by Mailpit. Although Mailpit is often used as a local development tool, this vulnerability allows remote exploitation via a web browser.

Scenario: A developer has Mailpit running at localhost:8025.
Trigger: The developer visits a malicious website (or a compromised legitimate site) in the same browser.
Exploitation: The malicious site's JavaScript initiates a WebSocket connection to ws://localhost:8025/api/events. Since the origin check is disabled, the browser allows this cross-origin connection.
Data Leak: The attacker receives all broadcasted events, including full email details (subjects, sender/receiver info) and server metrics.

Attack Impact

Real-time notification of new emails
Email metadata (sender, subject, recipients)
Mailbox statistics
All WebSocket broadcast data

Recommended Fix The CheckOrigin function should be removed to allow gorilla/websocket to enforce its default safe behavior (checking that the Origin matches the Host). Alternatively, strict validation logic should be implemented.

Proposed Change (Remove unsafe check):

var upgrader = websocket.Upgrader{
    ReadBufferSize:    1024,
    WriteBufferSize:   1024,
    // CheckOrigin: func(r *http.Request) bool { return true }, // REMOVED
    EnableCompression: true,
}

Proof of Concept (PoC): To reproduce this vulnerability:

Start Mailpit (default settings).
Save the following HTML code as poc.html and serve it from a different origin (e.g., using python http.server on port 8000 or opening it directly as a file).
Open the poc_websocket_hijack.html file in your browser.
Send a test email to Mailpit or perform any action in the Mailpit UI.
Observe that the "malicious" page successfully receives the event data.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/axllent/mailpit`	≥ 1.2.6&&< 1.28.2	1.28.2
🐹Go	`github.com/axllent/mailpit`	all versions	0.0.0-20260110031614

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/axllent/mailpit. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/axllent/mailpit to 1.28.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-524m-q5m7-79mm is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-524m-q5m7-79mm is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-524m-q5m7-79mm. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

**Summary** The Mailpit WebSocket server is configured to accept connections from any origin. This lack of Origin header validation introduces a Cross-Site WebSocket Hijacking (CSWSH) vulnerability. An attacker can host a malicious website that, when visited by a developer running Mailpit locally, establishes a WebSocket connection to the victim's Mailpit instance (default ws://localhost:8025). This allows the attacker to intercept sensitive data such as email contents, headers, and server statistics in real-time. **Vulnerable Code** The vulnerability exists in server/websockets/client.go wh

O3 Security · Impact-Aware SCA

Is GHSA-524m-q5m7-79mm in your dependencies?

O3 detects GHSA-524m-q5m7-79mm across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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