CVE-2021-30185
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 · uneditedCERN Indico before 2.3.4 can use an attacker-supplied Host header in a password reset 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 · high confidenceCERN Indico before 2.3.4 is vulnerable to Host Header Injection in its password reset functionality. An attacker can supply a malicious Host header value when requesting a password reset, causing the generated password reset link to point to an attacker-controlled domain. This allows the attacker to intercept password reset tokens by phishing users with legitimate-looking but attacker-hosted reset URLs.
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< 2.3.4CVSS 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
- None
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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 checksWork through these to decide whether this CVE applies to you.
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Determine installed Indico versionCheck the Indico version by examining the version file, running 'indico --version', or viewing the version displayed in the administration interfaceAffected if The version displayed is below 2.3.4
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Confirm password reset is accessibleVerify that the password reset functionality is available and functional in your Indico installation by accessing the reset request pageAffected if The password reset feature is enabled and operational (the vulnerability exists in this feature by default)
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Review Host header handlingInspect your web server configuration (Apache, Nginx, etc.) to see if there are any restrictions on acceptable Host header values, or check if Indico has any Host validation configuredAffected if No explicit Host header validation is configured, meaning the application may accept arbitrary Host header values
You are affected if your Indico installation is version 2.3.4 or lower and the password reset functionality is accessible without Host header validation in place.
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 data2.3.4
Upgrade to CERN Indico version 2.3.4 or later which implements proper Host header validation. As a temporary workaround, configure the web server to reject unexpected Host headers and ensure the application only generates reset links using a trusted, validated hostname.
- Consultation2.0 h
- Implementation3.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,272.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-30185 — 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-2021-30185 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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- 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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