CVE-2021-30185 — indico
HIGHCVE-2021-30185 is a high-severity (CVSS 7.5) vulnerability in indico. A fix is available for indico — see the affected versions and patch details below.
Indico Tampering with links (e.g. password reset) in sent emails
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-30185 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
indicoReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Impact
An external audit of the Indico codebase has discovered a vulnerability in Indico's URL generation logic which could have allowed an attacker to make Indico send a password reset link with a valid token pointing to an attacker-controlled domain by sending that domain in the Host header. Had a user clicked such a link without realizing it does not point to Indico (and that they never requested it), it would have revealed their password reset token to the attacker, allowing them to reset the password for that user and thus take over their Indico account.
- If the web server already enforces a canonical host name, this cannot be exploited (this was not part of the default config from the Indico setup guide)
- If only SSO is used (
LOCAL_IDENTITIESset toFalse), the vulnerability cannot be exploited for password reset links, but other links in emails set by Indico could be tampered with in the same way (with less problematic impact though)
Patches
You need to update to Indico 2.3.4 as soon as possible. See the docs for instructions on how to update.
Workarounds
You can configure the web server to canonicalize the URL to the hostname used for Indico. See this commit for the changes in our setup docs; they can be easily applied to your existing web server config.
For more information
If you have any questions or comments about this advisory:
- Open a thread in our forum
- Email us privately at [email protected]
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | indico | all versions | 2.3.4pip install --upgrade 'indico==2.3.4' |
Affected Products
indicocernDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for indico, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update indico to 2.3.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-30185 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2021-30185 in your dependencies?
Find it across PyPI, including transitive dependencies.