CriticalCVE-2017-16651

    Roundcube Webmail File Disclosure Vulnerability (CVE-2017-16651)

    Published In CISA KEV since Sources: CVE.org

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    What is affected, what to do

    Roundcube Webmail before 1.1.10, 1.2.x before 1.2.7, and 1.3.x before 1.3.3 allows unauthorized access to arbitrary files on the host's filesystem, including configuration files, as exploited in the wild in November 2017. The attacker must be able to authenticate at the target system with a valid username/password as the attack requires an active session. The issue is related to file-based attachment plugins and _task=settings&_action=upload-display&_from=timezone requests.

    The vulnerability is being actively exploited; treat it as a priority. The available sources name no fixed version. Check the vendor guidance in the references below. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Roundcube Webmail lte *..1.1.9
    • Roundcube Webmail eq 1.2.0..1.2.0
    • Roundcube Webmail eq 1.2.1..1.2.1
    • Roundcube Webmail eq 1.2.2..1.2.2
    • Roundcube Webmail eq 1.2.3..1.2.3
    • Roundcube Webmail eq 1.2.4..1.2.4
    • Roundcube Webmail eq 1.2.5..1.2.5
    • Roundcube Webmail eq 1.2.6..1.2.6
    • Roundcube Webmail eq 1.3.0..1.3.0
    • Roundcube Webmail eq 1.3.1..1.3.1
    • Roundcube Webmail eq 1.3.2..1.3.2
    • Debian Linux eq 7.0..7.0
    • Debian Linux eq 9.0..9.0

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

    Metrics

    7.8

    Priority

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

    Source: NVD, CVSS v3

    7.8

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: CVE.org

    45.7 %

    EPSS score

    Elevated — model estimates 10-50% exploitation likelihood.

    Source: FIRST EPSS, percentile 98.8

    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
    217.09 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 exploited
    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
    7.8 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
    7.8
    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
    45.7 %
    Elevated — model estimates 10-50% exploitation likelihood.
    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
    98.8
    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 4 February 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-552

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This CVE is on KEV because it was actively exploited in November 2017 to exfiltrate Roundcube configuration files containing DB credentials, the des_key and IMAP/SMTP passwords — an ideal pivot for mailbox takeover and lateral movement. Although the attacker needs a valid session, credentials from phishing, credential stuffing and infostealer logs are commodity goods, so exploitation likelihood is high. Treat as high priority if Roundcube is internet-exposed or runs user accounts without MFA, typical for hosters, universities and SMBs with self-hosted webmail. No known ransomware use, but the flaw is a recurring entry vector for BEC and mailbox-takeover operations.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Upgrade Roundcube to a patched release: 1.1.10, 1.2.7 or 1.3.3 (or newer). For Debian-packaged installs (debian_linux 7/9), pull the current security update from the distribution repo (apt-get update && apt-get install roundcube).
      • If patching cannot happen immediately, block the vulnerable path ?_task=settings&_action=upload-display&_from=timezone at the reverse proxy (nginx/Apache/HAProxy) until the update is deployed.
      • Invalidate all active Roundcube sessions (flush the session store, DELETE FROM session; in the Roundcube DB) and force users to re-authenticate so any hijacked sessions are killed.
      • Audit configuration files for compromise: config/config.inc.php holds DB credentials, the des_key and often SMTP/IMAP passwords. If exposure is suspected, regenerate des_key, rotate the DB user password and all mail-service credentials.
      • Tighten file permissions for sensitive files relative to the web server user: /etc/shadow must not be world-readable; set config/config.inc.php to chmod 640 with owner root:www-data.

    2. Runbook step 2

      Mitigation layers

      • WAF / reverse-proxy rule: deny requests to /_action=upload-display carrying _from=timezone combined with path-traversal patterns (../, URL-encoded %2e%2e, absolute paths /etc/, /var/). nginx example: if ($args ~* "_action=upload-display.*_from=timezone") { return 403; }.
      • Network segmentation: place the Roundcube host behind a reverse proxy terminating TLS; the webmail host's 80/443 ports should not be directly internet-reachable. Administrative interfaces (SSH, DB) only via jump host.
      • Authentication hardening: enforce MFA for webmail logins (e.g. via the twofactor_gauthenticator plugin), account lockout on repeated failures, and fail2ban rules against roundcube.log. The flaw requires valid credentials — MFA neutralises stolen passwords.
      • Constrain filesystem access for the web-server user (www-data) via AppArmor/SELinux profiles: allow Roundcube's install directory, /tmp, logs and required library paths only; explicitly deny read access to /etc/, /root/ and other users' home directories.
      • Review attachment plugins: the default database_attachments and filesystem_attachments plugins are involved. Prefer database_attachments and keep temp_dir outside of paths an attacker might target via traversal.

    3. Runbook step 3

      Detection rules

      • Web-server access log: GET/POST requests containing _task=settings&_action=upload-display&_from=timezone combined with ../ or absolute paths. Sigma-shaped: selection: cs-uri-query|contains_all: ['_action=upload-display', '_from=timezone'] AND cs-uri-query|re: '(\.\./|%2e%2e|/etc/|/var/)'.
      • Response monitoring: HTTP 200 responses to upload-display requests with unusually large bodies or a Content-Type mismatch (text where an image is expected) indicate successful file disclosure.
      • Roundcube logs (logs/errors, logs/userlogins): successful logins from unusual geolocations/ASNs immediately followed by settings activity — correlate on session ID.
      • Linux auditd on the host: -w /etc/passwd -p r -k roundcube_fileread and equivalents for /etc/shadow and config/config.inc.php. Alert on reads by the web-server UID outside normal boot/startup windows.
      • EDR / Sysmon-for-Linux: process chain php-fpm/apache2 → unexpected reads of sensitive paths. KQL shape: DeviceFileEvents | where InitiatingProcessFileName in ('php-fpm','apache2','httpd') and FolderPath startswith '/etc/'.

    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 1.1.10, 1.2.x before 1.2.7, and 1.3.x before 1.3.3 allows unauthorized access to arbitrary files on the host's filesystem, including configuration files, as exploited in the wild in November 2017. The attacker must be able to authenticate at the target system with a valid username/password as the attack requires an active session. The issue is related to file-based attachment plugins and _task=settings&_action=upload-display&_from=timezone requests.

    Source: NVD (NIST), 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
    • 1.3.1
    • 1.2.3
    • 1.2.6
    • 1.3.0
    • 1.2.5
    • 1.3.2
    • 1.2.2
    • 1.2.4
    • ≤ 1.1.9
    • 1.2.0
    • 1.2.1
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebiandebian_linux7.0
    Linuxdebiandebian_linux9.0

    Weakness classes (CWE)

    • CWE-552Files or Directories Accessible to External Parties

      Base

      The product makes files or directories accessible to unauthorized actors, even though they should not be.

      Entry at MITRE CWE-552

    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
    Packet StormRoundcube Webmail 1.2 File Disclosure (opens in a new tab)packetstormsecurity.comPoC (publicly reported)reported, not verified—

    References & sources

    • github.comroundcube/roundcubemail/releases/tag/1.3.3x_refsource_CONFIRM, Issue tracking, Release notes, Third-party advisory
    • roundcube.netnews/2017/11/08/security-updates-1.3.3-1.2.7-and-1.1.10x_refsource_CONFIRM, Issue tracking, Vendor advisory
    • lists.debian.org[debian-lts-announce] 20171128 [SECURITY] [DLA 1193-1] roundcube security updateMailing list, x_refsource_MLIST, Mailing list, Third-party advisory
    • github.comroundcube/roundcubemail/releases/tag/1.1.10x_refsource_CONFIRM, Issue tracking, Release notes, Third-party advisory
    • securityfocus.com101793Vulnerability database, x_refsource_BID, Third-party advisory, Vulnerability database
    • github.comroundcube/roundcubemail/releases/tag/1.2.7x_refsource_CONFIRM, Issue tracking, Release notes, Third-party advisory
    • debian.orgDSA-4030Vendor advisory, x_refsource_DEBIAN, Issue tracking, Third-party advisory
    • github.comroundcube/roundcubemail/issues/6026x_refsource_CONFIRM, Issue tracking, Patch, Third-party advisory
    • packetstormsecurity.comfiles/161226/Roundcube-Webmail-1.2-File-Disclosure.htmlx_refsource_MISC, Exploit, Third-party advisory, Vulnerability database
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2017-16651government-resource, US government resource
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