CVE-2020-6795
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 · uneditedWhen processing a message that contains multiple S/MIME signatures, a bug in the MIME processing code caused a null pointer dereference, leading to an unexploitable crash. This vulnerability affects Thunderbird < 68.5.
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 confidenceA null pointer dereference vulnerability exists in Thunderbird's MIME processing code when handling messages containing multiple S/MIME signatures. The bug causes an unexploitable crash (denial of service) but cannot be leveraged for code execution.
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< 68.5.0CVSS 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
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
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 checksWork through these to decide whether this CVE applies to you.
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Check if Thunderbird is installedOn Linux: dpkg -l | grep thunderbird or which thunderbird. On Windows: Check Program Files or via PowerShell Get-ItemProperty 'HKLM:\SOFTWARE\Mozilla\Mozilla Thunderbird' or check C:\Program Files\Mozilla Thunderbird. On macOS: ls /Applications | grep ThunderbirdAffected if Thunderbird is not found on the system - not applicable
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Determine installed Thunderbird versionRun thunderbird --version from command line, or open Thunderbird and go to Help > About Thunderbird, or check the application properties in Programs and Features (Windows)Affected if Version is missing or cannot be determined - cannot assess
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Compare version to affected rangeCompare the installed version number to 68.5.0. The affected range is any version less than 68.5.0 (e.g., 68.4.x, 68.3.x, 60.x, etc.)Affected if Installed version is 68.4.x or lower, or any version less than 68.5.0 - user IS affected
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Verify S/MIME usage (context for exploitability)Check if S/MIME signing is configured in Thunderbird: Go to Account Settings > End-to-End Encryption, or inspect configured certificates for signing. S/MIME requires a signing certificate to be set up.Affected if S/MIME signing is not configured - the vulnerability exists in the code but requires multiple S/MIME-signed messages to trigger the crash
User is affected if Thunderbird is installed with a version lower than 68.5.0 AND S/MIME signing is in use, as the crash occurs when processing messages containing multiple S/MIME signatures.
Generated from the published advisory. Verify against your own configuration.
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 data68.5.0
Upgrade Thunderbird to version 68.5 or later to resolve the null pointer dereference in the S/MIME signature processing code.
- Consultation1.0 h
- Implementation1.0 h
- Testing1.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-6795 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2020-6795 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- 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
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