dbcve.org
Enterprise Linux DesktopOperating system · Redhat

CVE-2018-5185

MEDIUM · 6.5 CVSS v3.0 Published 2018-06-11
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
72/100
Remediation priority · Elevated
Remotely reachable No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Plaintext of decrypted emails can leak through by user submitting an embedded form. This vulnerability affects Thunderbird ESR < 52.8 and Thunderbird < 52.8.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

In Thunderbird versions before 52.8, decrypted email plaintext can leak through embedded forms. When a user views a decrypted email (S/MIME or PGP) containing an HTML form and submits that form, the plaintext content of the decrypted email is transmitted alongside the form data, allowing sensitive decrypted content to be exfiltrated.

MitigationUpgrade Thunderbird to version 52.8 or later (or current stable) to patch the vulnerability. Users should not submit forms embedded in emails from untrusted senders as a defense-in-depth measure.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Enterprise Linux DesktopOperating system
Affected:= 6.0= 7.0
Enterprise Linux ServerOperating system
Affected:= 6.0= 7.0
Enterprise Linux Server AusOperating system
Affected:= 7.6
Enterprise Linux Server EusOperating system
Affected:= 7.5= 7.6
Enterprise Linux Server TusOperating system
Affected:= 7.6
Enterprise Linux WorkstationOperating system
Affected:= 6.0= 7.0
Debian LinuxOperating system
Affected:= 7.0= 8.0= 9.0
Ubuntu LinuxOperating system
Affected:= 14.04= 16.04= 17.10= 18.04

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Thunderbird version
    Run 'thunderbird --version' from terminal, or check via package manager: 'dpkg -l | grep thunderbird' (Debian/Ubuntu) or 'rpm -qa | grep thunderbird' (RHEL). On Ubuntu you can also check via 'snap list thunderbird' or 'apt show thunderbird'.
    Affected if Version is lower than 52.8.0 (e.g., 52.7.0, 52.6.0, etc.)
  2. Verify S/MIME or PGP encryption is in use
    Check if Thunderbird has S/MIME certificates configured (Account Settings > End-to-End Encryption) or if Enigmail/PGP plugin is installed and enabled. Look for encryption keys configured in the security settings of each email account.
    Affected if S/MIME or PGP encryption is actively configured and used for receiving/decrypting emails
  3. Confirm HTML email rendering is enabled
    In Thunderbird, go to View > Message Body As (or Account Settings > Composition > General) and verify that 'HTML' is selected rather than 'Plain Text'. Alternatively, check the global preferences file (~/.thunderbird/*.default/prefs.js) for 'mailnews.display.html_as' set to 1 or similar.
    Affected if HTML rendering is enabled (emails display with HTML formatting rather than plain text only)
  4. Identify presence of embedded forms in email handling
    This is a behavioral condition: the vulnerability triggers when a user views a decrypted S/MIME or PGP email containing an HTML <form> element and then submits that form. There is no config to check; the risk exists if the user receives and interacts with such emails.
    Affected if User views decrypted S/MIME or PGP emails with HTML forms and submits those forms

User is affected if Thunderbird version is below 52.8 AND they use S/MIME or PGP decryption while viewing HTML emails that may contain embedded forms.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade Thunderbird to version 52.8 or later (or current stable) to patch the vulnerability. Users should not submit forms embedded in emails from untrusted senders as a defense-in-depth measure.

Fix this in Enterprise Linux Desktop Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2018-5185 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data