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Debian LinuxOperating system · Debian

CVE-2018-5184

HIGH · 7.5 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 →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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
Using remote content in encrypted messages can lead to the disclosure of plaintext. 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, when handling encrypted email messages that contain remote content (such as external images), the act of loading this remote content can leak information about the encrypted message plaintext. This occurs because the external request made to fetch remote content can reveal information about what the encrypted message contains, effectively breaking the confidentiality of encrypted email.

MitigationUpgrade Thunderbird and Thunderbird ESR to version 52.8 or later. Until upgraded, avoid opening encrypted messages that may contain remote content, or disable automatic loading of remote content in Thunderbird settings.

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
Debian LinuxOperating system
Affected:= 7.0= 8.0= 9.0
Ubuntu LinuxOperating system
Affected:= 14.04= 16.04= 17.10= 18.04
Enterprise LinuxOperating system
Affected:= 6.0= 7.0
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

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
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/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 if Thunderbird is installed
    Run `which thunderbird` on Linux systems, or check via package manager: `dpkg -l | grep thunderbird` (Debian/Ubuntu) or `rpm -qa | grep thunderbird` (RHEL)
    Affected if Thunderbird is not installed on the system
  2. Determine the installed Thunderbird version
    Run `thunderbird --version` or check via package manager: `dpkg -s thunderbird` (Debian/Ubuntu) or `rpm -qi thunderbird` (RHEL)
    Affected if The installed version is below 52.8 (e.g., 52.7.x, 52.6.x, earlier versions)
  3. Verify the remote content loading setting in Thunderbird
    Open Thunderbird, go to Account Settings > [select account] > Privacy > check if 'Allow remote content in messages' is enabled. Alternatively, check the prefs.js configuration file in the Thunderbird profile directory for `mailnews.messageDisplay.disableRemoteImage` set to false
    Affected if Remote content loading is enabled (the checkbox is checked or `mailnews.messageDisplay.disableRemoteImage` is not set to true)
  4. Confirm the vulnerability condition
    Cross-reference: version < 52.8 AND remote content loading is enabled for accounts handling encrypted email
    Affected if Both conditions are true: Thunderbird version is before 52.8 AND automatic loading of remote content is enabled in settings

You are affected if Thunderbird version is earlier than 52.8 and the setting to automatically load remote content (such as external images) in email messages is enabled.

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 and Thunderbird ESR to version 52.8 or later. Until upgraded, avoid opening encrypted messages that may contain remote content, or disable automatic loading of remote content in Thunderbird settings.

Fix this in Debian Linux Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $860
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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-2018-5184 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