CVE-2025-69412

Executive Summary

CVE-2025-69412 is a security advisory affecting KDE messagelib, a library used for email message handling in KDE applications. The vulnerability lies in the handling of SSL errors when communicating with the Google Safe Browsing Lookup API (also known as the phishing API). Specifically, the library ignores SSL certificate validation errors for threatMatches:find requests, which could allow an attacker to spoof threat data. This could lead to a user being misled about the safety of a URL, potentially increasing the risk of phishing attacks. The CVSS score is 3.4 (Low), and the EPSS score is 0.0%, indicating a low probability of exploitation in the wild. The vulnerability is present in versions before 25.11.90, and the patch status is confirmed as patched in that version.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a KDE library (messagelib) used in desktop applications.

CVSS Breakdown & Threat Level

• CVSS Score: 3.4 (Low)
• Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N
• Attack Vector (AV): Network – The vulnerability is exploitable over the network.
• Attack Complexity (AC): High – Successful exploitation requires an attacker to perform a man-in-the-middle (MITM) attack or control a network path to intercept and modify traffic.
• Privileges Required (PR): None – No authentication is required.
• User Interaction (UI): Required – The user must be using an application that relies on messagelib and triggers a Safe Browsing lookup.
• Scope (S): Unchanged – The vulnerability does not affect other components.
• Confidentiality (C): None – No data is exposed.
• Integrity (I): Low – An attacker can spoof threat data, potentially causing the application to misclassify a malicious URL as safe.
• Availability (A): None – No impact on system availability.

Threat Level: Low. The vulnerability requires a MITM attack and user interaction, and the default configuration does not contact the Lookup API.

Deep Dive & Mechanics

The vulnerability is in the messagelib library, specifically in the code that handles the Google Safe Browsing Lookup API. The API is used to check URLs against Google's list of known phishing and malware sites. The library makes HTTP requests to the API endpoint and is supposed to validate the SSL/TLS certificate of the server to ensure the connection is secure and the response is authentic.

The flaw is that the library ignores SSL certificate validation errors for threatMatches:find requests. This means that if an attacker can perform a man-in-the-middle attack (e.g., on a compromised network), they can present a fake SSL certificate, and the library will still accept the response. The attacker can then send a crafted response that falsely indicates a malicious URL is safe, or vice versa.

The attack flow:

1. User clicks a link in an email or performs an action that triggers a Safe Browsing lookup.
2. The application (using messagelib) sends a request to the Google Safe Browsing API.
3. An attacker intercepts the request (MITM) and responds with a forged SSL certificate and a malicious response.
4. The library ignores the SSL error and processes the attacker's response.
5. The user is misled about the safety of the URL.

The vulnerability is mitigated by the fact that the Lookup API is not contacted in the default configuration of messagelib. It must be explicitly enabled by the user or administrator.

Vulnerable vs. Patched Code

The vulnerable code is in the messagelib library, likely in a file that handles HTTP requests to the Safe Browsing API. The exact code is not publicly available, but the fix involves ensuring that SSL certificate validation is enforced for all API requests.

Vulnerable Code (Conceptual):

// In some HTTP client code
QNetworkReply *reply = manager->get(request);
// SSL errors are ignored
connect(reply, &QNetworkReply::sslErrors, [](const QList<QSslError> &errors) {
    // Ignore all SSL errors
    reply->ignoreSslErrors();
});

Patched Code (Conceptual):

// In some HTTP client code
QNetworkReply *reply = manager->get(request);
// SSL errors are handled properly
connect(reply, &QNetworkReply::sslErrors, [](const QList<QSslError> &errors) {
    // Log errors and abort if any are present
    for (const QSslError &error : errors) {
        qWarning() << "SSL error:" << error.errorString();
    }
    reply->abort();
});

The patch ensures that SSL errors are not ignored, and the request is aborted if any SSL certificate validation fails.

Exploitation & Lab Setup

Red Team (Attacker)

Prerequisites:

• A network position allowing man-in-the-middle attacks (e.g., compromised Wi-Fi, ARP spoofing).
• A target using KDE messagelib with the Safe Browsing API enabled.
• Knowledge of the API endpoint and request format.

Lab Setup:

1. Set up a MITM proxy (e.g., mitmproxy, Bettercap).
2. Configure the proxy to intercept traffic to safebrowsing.googleapis.com.
3. Generate a self-signed SSL certificate for the domain.
4. When the target application makes a request, respond with the forged certificate and a crafted JSON response.

Example Exploit (Python with mitmproxy):

from mitmproxy import http

def request(flow: http.HTTPFlow) -> None:
    if "safebrowsing.googleapis.com" in flow.request.pretty_host:
        # Forge a response indicating the URL is safe
        flow.response = http.HTTPResponse.make(
            200,
            b'{"matches": []}',
            {"Content-Type": "application/json"}
        )

Note: No public exploit code is available for this CVE.

Blue Team (Defender)

Detection:

• Monitor for SSL/TLS certificate errors in application logs.
• Use network monitoring to detect MITM attacks (e.g., ARP spoofing, rogue DHCP).
• Ensure the Safe Browsing API is disabled unless explicitly needed.

Mitigation:

• Update to KDE messagelib version 25.11.90 or later.
• Disable the Safe Browsing Lookup API in the application configuration.
• Use certificate pinning or additional TLS validation in custom applications.

Indicators of Compromise (IOCs)

• Network: Unexpected SSL certificate errors for safebrowsing.googleapis.com.
• Logs: Application logs showing SSL errors being ignored.
• Configuration: The Safe Browsing API being enabled in messagelib configuration.
• Process: Unusual network traffic to safebrowsing.googleapis.com with invalid certificates.

Detection Engineering

YARA Rule

rule CVE_2025_69412_KDE_SSL_Ignore {
    meta:
        description = "Detects KDE messagelib ignoring SSL errors for Safe Browsing API"
        author = "Valters IT"
        date = "2025-04-01"
        cve = "CVE-2025-69412"
    strings:
        $s1 = "ignoreSslErrors" ascii wide nocase
        $s2 = "threatMatches:find" ascii wide nocase
        $s3 = "safebrowsing.googleapis.com" ascii wide nocase
    condition:
        all of ($s*)
}

Sigma Rule

title: KDE messagelib SSL Error Ignored for Safe Browsing API
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects when KDE messagelib ignores SSL errors for Google Safe Browsing Lookup API
author: Valters IT
date: 2025-04-01
logsource:
    product: linux
    service: syslog
detection:
    selection:
        - "SSL error ignored for safebrowsing.googleapis.com"
        - "ignoreSslErrors"
    condition: selection
falsepositives:
    - Legitimate use of ignoreSslErrors in other contexts
level: low

Suricata Rule

alert tls any any -> any any (msg:"CVE-2025-69412 - KDE messagelib ignoring SSL errors for Safe Browsing API"; flow:to_server; tls.cert_issuer:!="Google Trust Services"; tls.cert_subject:!="*.googleapis.com"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Update KDE messagelib to version 25.11.90 or later.
2. Disable the Google Safe Browsing Lookup API in the application configuration if not required.
3. Monitor for SSL certificate errors in application logs.

Long-term Measures:

• Implement certificate pinning for critical API endpoints.
• Use network security controls (e.g., TLS inspection, IDS/IPS) to detect MITM attacks.
• Regularly update all KDE components.

Patch Details:

• Upgrade to KDE messagelib version 25.11.90 or later.
• The patch is available from the KDE project.

Valters IT