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Introduction:
A decade-old vulnerability in the Roundcube webmail client has escalated to a major security risk, thanks to the release of proof-of-concept (PoC) code that makes it easier for threat actors to exploit. The flaw, identified as CVE-2025-49113, has a severity score of 9.9, and poses a significant threat to webmail servers. This article delves into the details of the vulnerability, its potential consequences, and the steps organizations need to take to protect themselves.
Original
The vulnerability, CVE-2025-49113, affects Roundcube versions from 1.1.0 to 1.6.10, and it allows authenticated attackers to execute arbitrary code on the server. The root cause of this issue lies in improper sanitization of the “_from” parameter used in Roundcube’s image upload feature. Exploiting this bug enables attackers to hijack the server, install backdoors, steal data, and potentially conduct lateral attacks. This vulnerability has remained hidden for over a decade, making it particularly dangerous now that PoC code is available.
The vulnerability was disclosed by security researcher Kirill Firsov, who has urged organizations to upgrade to the latest Roundcube versions—1.6.11 or 1.5.10—released on June 1, 2025. The bug requires an attacker to be authenticated, but in practice, this barrier is low as attackers can steal or guess login credentials. As evidence of this, a Belarusian hacker group, UNC1151, has already begun targeting Roundcube users in Poland through a different vulnerability (CVE-2024-42009). Experts believe that combining CVE-2025-49113 with credential theft could create a highly effective attack chain.
The impact is wide-reaching, with over 85,000 unpatched instances of Roundcube identified globally, primarily in Europe. Given Roundcube’s popularity among individuals, businesses, and hosting providers, the vulnerability poses a significant risk to various sectors. Other recent vulnerabilities, such as CVE-2023-43770 and CVE-2023-5631, have already been exploited in various campaigns, indicating the growing focus on Roundcube by cybercriminals.
What Undercode Says:
The CVE-2025-49113 vulnerability is a wake-up call for all organizations using Roundcube webmail. Despite being a decade-old flaw, the recent escalation in threat activity, including the availability of PoC code and the quick weaponization of the vulnerability, indicates that cybercriminals are actively targeting this weakness. The fact that many organizations have left their Roundcube servers unpatched for so long only exacerbates the situation.
Roundcube is a widely used open-source webmail client, popular due to its ease of use and privacy features. However, its widespread adoption has made it a prime target for attackers. Given its integration with numerous web hosting services like GoDaddy and Dreamhost, the potential impact of this vulnerability is far-reaching. Organizations that have not prioritized regular updates and patches are at high risk.
What makes this vulnerability particularly alarming is its post-authentication nature. While attackers need to have valid login credentials to exploit the flaw, the ease with which credentials can be stolen or guessed makes this condition less of a barrier. Additionally, the fact that it can be used to gain full control of the server opens up possibilities for further attacks, including data theft and deployment of malware. As such, businesses that rely on Roundcube must act quickly to patch their systems, ensuring they are using the latest versions.
The emergence of credential-theft campaigns, particularly in Poland, highlights how attackers can chain vulnerabilities to escalate their attacks. The Belarusian hacker group UNC1151’s activity is a stark reminder that cybercriminals are constantly evolving their tactics. The exploitation of CVE-2025-49113 in conjunction with other flaws is likely to become a common attack vector in the coming months.
Given the global presence of vulnerable Roundcube installations, including in critical sectors, organizations must not ignore the patching urgency. The longer a system remains unpatched, the higher the risk of a data breach or worse.
Fact Checker Results:
✅ The vulnerability CVE-2025-49113 exists and has been verified by multiple security researchers, including Kirill Firsov.
✅ The PoC code for this vulnerability has been publicly released, increasing the risk of exploitation.
✅ The CVSS score for this flaw is 9.9, indicating its critical severity and potential for exploitation.
Prediction:
❌ The risk of mass exploitation is highly probable, especially given the availability of PoC code.
✅ Organizations that delay patching may face data breaches or system hijacks within weeks, as attackers quickly reverse-engineer the available fixes.
✅ A rise in cyber-espionage campaigns targeting Roundcube users is expected, especially in regions where the software is heavily used by government and business sectors.
References:
Reported By: www.darkreading.com
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