CriticalCVE-2025-49113

    RoundCube Webmail Deserialization of Untrusted Data Vulnerability (CVE-2025-49113)

    Published In CISA KEV since Sources: Debian LTS, Debian, pwn.watch, CVE.org, OSV

    Share

    What is affected, what to do

    Roundcube Webmail before 1.5.10 and 1.6.x before 1.6.11 allows remote code execution by authenticated users because the _from parameter in a URL is not validated in program/actions/settings/upload.php, leading to PHP Object Deserialization.

    The vulnerability is being actively exploited; treat it as a priority. Update Roundcube Webmail to version 1.5.10, Roundcube Webmail to version 1.6.11. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Roundcube Webmail lt *..1.5.10
    • Roundcube Webmail lt 1.6.0..1.6.11
    Fixed in
    • Roundcube Webmail 1.5.10
    • Roundcube Webmail 1.6.11

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    9.9

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: Vendor (CNA), CVSS v3

    9.9

    CVSS v3

    Severity Critical on the scale from 0 to 10.

    Source: Debian LTS, Debian, pwn.watch, CVE.org, OSV

    99.49 %

    EPSS score

    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.

    Source: FIRST EPSS, percentile 99.94

    Show all metrics
    Severity
    Critical
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    238.58 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    actively exploitedSource: VulnCheck KEV (opens in a new tab), ANSSI / CERT-FR How we classify
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    9.9 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    9.9
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    99.49 %
    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    99.94
    Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    Actively exploited
    Published
    In CISA KEV since

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    CISA assessment (SSVC)
    Exploitation: active · not automatable · Technical impact: total
    Source: CISA Vulnrichment, as of 10 June 2025
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-502

    Response and mitigation

    Why act now?

    Prioritisation rationale

    The flaw yields direct remote code execution as the web-server user from a single crafted URL once any mailbox account is logged in; the technical bar is low and public proof-of-concept exploitation is available. Exploitation likelihood ranks among the very highest EPSS has observed, and CISA added the CVE to KEV on a tight timeline for good reason. For NIS2-scoped organisations exposing Roundcube to the internet — typical for universities, hosters, municipalities and smaller public bodies — this is a P1 patch: one leaked employee password, abundantly available in credential dumps, is enough to pivot into full mail-server compromise, lateral movement and data exfiltration. No confirmed ransomware use is flagged by CISA, which only marginally lowers urgency since mail-server RCE is a prized initial-access vector regardless of the follow-on tooling.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Upgrade Roundcube to 1.6.11 (for the 1.6.x branch) or 1.5.10 (for 1.5.x) immediately; for Composer-based installs run composer update roundcube/roundcubemail and verify the patch landed in program/actions/settings/upload.php.
      • On Debian 11 apply the vendor packages via apt-get update && apt-get install --only-upgrade roundcube roundcube-core, then confirm with dpkg -l | grep roundcube.
      • If patching cannot complete within hours, restrict webmail login to admin/operational accounts via htaccess allowlist or reverse-proxy ACL, or take the instance offline — exploitation requires valid credentials, but phished mailbox passwords are a realistic prerequisite.
      • Invalidate all Roundcube sessions (truncate the session table in the Roundcube database) and force password rotation on every mail account, since existing sessions survive the upgrade otherwise.
      • Inspect the PHP runtime user (www-data/apache) and the Roundcube temp/ directory for stray serialised objects, webshells and new PHP files; preserve forensic images of suspicious hosts before rebuild.

    2. Runbook step 2

      Mitigation layers

      • Network segmentation: place the webmail frontend behind a reverse proxy (nginx/HAProxy) with geo/ASN allowlisting for expected user regions; restrict egress from the webmail host to SMTP, IMAP and DNS only to cut off reverse shells.
      • WAF rule: block requests to /program/actions/settings/upload.php where the _from parameter deviates from an allowlist of known section names (identity, preferences, folders, …), and filter serialised PHP patterns (O:\d+:", a:\d+:{, s:\d+:") in request bodies and URL parameters.
      • Endpoint hardening: extend PHP disable_functions with exec, shell_exec, system, passthru, proc_open, popen where Roundcube can run without them; constrain open_basedir to the Roundcube install path and its temp/ directory.
      • IAM: enforce MFA on every mail account via a Roundcube 2FA plugin (twofactor_gauthenticator or similar) or an upstream IdP; retire or isolate shared/service mailboxes that still log into Roundcube.
      • Configuration: review config.inc.php — set enable_installer to false, rotate des_key (invalidates legacy session cookies), move temp_dir outside the document root and mount it noexec.
      • Monitor the temp/ directory with auditd (-w /var/lib/roundcube/temp -p wa) so file writes feeding the deserialisation chain become visible.

    3. Runbook step 3

      Detection rules

      • Web access logs: grep -E "upload\.php.*_from=" access.log — any request whose _from parameter contains URL-encoded serialisation markers (%7B, %3A, O%3A) is suspicious. Sigma shape: selection: cs-uri-stem endswith '/actions/settings/upload.php' and cs-uri-query contains '_from='.
      • Sysmon EID 1 / auditd execve: PHP process (php-fpm, apache2) spawning sh, bash, python, perl, curl, wget, nc — the standard post-exploitation chain following PHP object injection. KQL: DeviceProcessEvents | where InitiatingProcessFileName in ("php-fpm","httpd","apache2") and FileName in ("sh","bash","curl","wget","nc","python3").
      • Filesystem monitoring: new .php, .phtml or .phar files appearing in temp/, logs/ or anywhere beneath the Roundcube document root. Auditd rule: -a always,exit -F dir=/var/lib/roundcube -F perm=wa -F "name=~\.ph(p|tml|ar)$".
      • Network telemetry (Zeek/Suricata): outbound connections from the webmail host to destinations outside the expected set (mailstore, package mirrors), especially on high ports or to newly registered domains.
      • SIEM correlation: a successful Roundcube login (IMAP/application log) followed within 60 s by an upload.php request carrying _from= and a shell child process on the same host — high-fidelity alert.

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    Roundcube Webmail before 1.5.10 and 1.6.x before 1.6.11 allows remote code execution by authenticated users because the _from parameter in a URL is not validated in program/actions/settings/upload.php, leading to PHP Object Deserialization.

    Source: Debian LTS Advisories, Debian Security Advisories, pwn.watch, NVD (NIST), OSV (Open Source Vulnerabilities), cvelistv5, CISA KEV Catalog, CVE.org (MITRE)

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    RoundcubeWebmail
    • 1.6.0 – < 1.6.11
    • < 1.5.10
    • 1.6.11
    • 1.5.10
    roundcubewebmail
    • 1.6.0 – < 1.6.11
    • < 1.5.10
    • 1.6.11
    • 1.5.10
    packagistroundcube/roundcubemail
    • —
    • 1.6.0
    • —
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebiandebian_linux11.0
    Linuxdebianroundcubebookworm
    Linuxdebianroundcubebullseye

    Weakness classes (CWE)

    • CWE-502Deserialization of Untrusted Data

      Base

      The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.

      Entry at MITRE CWE-502

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    CISA KEV CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited
    ANSSI / CERT-FRLicence Ouverte 2.0, as of CERTFR-2025-ALE-008 – [MàJ] Vulnérabilité dans Roundcube (clôturée 2025-07-21) (opens in a new tab)cert.cyber.gouv.fractively exploited

    References & sources

    • NVD (NIST)NVD: CVE-2025-49113advisory, pwn-watch
    • github.comroundcube/roundcubemail/pull/9865web, Issue tracking
    • github.comroundcube/roundcubemail/commit/0376f69e958a8fef7f6f09e352c541b4…web, Patch
    • github.comroundcube/roundcubemail/commit/7408f31379666124a39f9cb1018f62bc…web, Patch
    • github.comroundcube/roundcubemail/commit/c50a07d88ca38f018a0f4a0b008e9a1d…web, Patch
    • fearsoff.orgresearch/roundcubeweb, Third-party advisory
    • github.comroundcube/roundcubemailpackage
    • github.comroundcube/roundcubemail/releases/tag/1.5.10web, Release notes
    • github.comroundcube/roundcubemail/releases/tag/1.6.11web, Release notes
    • lists.debian.orgdebian-lts-announce/2025/06/msg00008.htmlweb, Mailing list, Third-party advisory
    • roundcube.netRoundcube Webmail — CVE-2025-49113web, Vendor advisory, pwn-watch
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2025-49113web, government-resource, US government resource
    • vicarius.iovsociety/posts/cve-2025-49113-roundcube-mitigation-scriptweb, Exploit, Mitigation, Third-party advisory
    • vicarius.iovsociety/posts/cve-2025-49113-roundcube-vulnerability-detectionweb, Exploit, Mitigation, Third-party advisory
    • openwall.comlists/oss-security/2025/06/02/3web, Mailing list, Third-party advisory
    • cert.cyber.gouv.frANSSI / CERT-FR: CERTFR-2025-ALE-008 – [MàJ] Vulnérabilité dans Roundcube (clôturée 2025-07-21)cert-fr
    • pwn.watchpwn.watch: Roundcube Webmail: RoundCube Webmail Deserialization of Untrusted Data Vulnerabilitypwn-watch
    • roundcube.netRoundcube Webmail — CVE-2025-68461pwn-watch
    • NVD (NIST)NVD: CVE-2025-68461pwn-watch
    • cisa.govCISA Known Exploited Vulnerabilities Catalogpwn-watch

    Linked advisories

    Embed badge

    Show the severity and KEV status of this vulnerability on your site – with a link back here. The image is updated hourly.

    Badge preview for CVE-2025-49113
    <a href="https://intel.neosec.eu/en/cve/CVE-2025-49113"><img src="https://intel.neosec.eu/badge/cve/CVE-2025-49113.svg?lang=en" alt="CVE-2025-49113 – NEOSEC Intel" height="20"></a>