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Zulip ServerApplication · Zulip

CVE-2020-14194

MEDIUM · 5.4 CVSS v3.1 Published 2020-08-21
Fix available
A fix is available. Upgrade to 2.1.5 or later.
See remediation →
61/100
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
Zulip Server before 2.1.5 allows reverse tabnapping via a topic header link.

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 · moderate confidence

Zulip Server before 2.1.5 is vulnerable to reverse tabnapping (opener manipulation) via topic header links. Links with target='_blank' in topic headers can have the linked page access window.opener and redirect the original page to an attacker-controlled site.

MitigationUpgrade to Zulip Server 2.1.5 or later, which adds rel='noopener noreferrer' to external links in topic headers.

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
Zulip ServerApplication
Affected:< 2.1.5

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
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/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. Identify installed Zulip Server version
    Run `zulip --version` or check the /var/log/zulip/version.log file, or look at the Zulip administration interface under 'Server settings' to find the exact version number
    Affected if The installed version is any version before 2.1.5 (e.g., 2.1.4, 2.1.3, 2.0.x, 1.9.x)
  2. Verify topic headers with external links exist
    Navigate to any stream in Zulip and examine topic names. Look for topics that contain hyperlinks pointing to external websites
    Affected if There are topic headers containing links to external URLs (non-Zulip domains)
  3. Inspect HTML source of topic header links
    Right-click on any external link in a topic header and select 'Inspect' or 'View Page Source'. Examine the anchor tag to see if it contains `rel="noopener noreferrer"`
    Affected if The external links in topic headers lack the rel='noopener noreferrer' attribute, meaning they only have target='_blank' without the security attribute

You are affected if your Zulip Server version is below 2.1.5 AND you have external links in topic headers that are missing the rel='noopener noreferrer' attribute.

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
Upgrade available Upgrade to 2.1.5 or later
Fixed in 2.1.5
Interim mitigation

Upgrade to Zulip Server 2.1.5 or later, which adds rel='noopener noreferrer' to external links in topic headers.

Fix this in Zulip Server Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.

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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-2020-14194 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