CVE-2021-30185

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]

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_IDENTITIES set to False), 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)

CVE-2021-30185 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.3.4); upgrading removes the vulnerable code path.

Kodem intelligence

You need to update to Indico 2.3.4 as soon as possible.
See the docs for instructions on how to update.

1. What is CVE-2021-30185? CVE-2021-30185 is a high-severity security vulnerability in indico (pip), affecting versions < 2.3.4. It is fixed in 2.3.4.
2. How severe is CVE-2021-30185? CVE-2021-30185 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of indico are affected by CVE-2021-30185? indico (pip) versions < 2.3.4 is affected.
4. Is there a fix for CVE-2021-30185? Yes. CVE-2021-30185 is fixed in 2.3.4. Upgrade to this version or later.
5. Is CVE-2021-30185 exploitable, and should I be worried? Whether CVE-2021-30185 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2021-30185 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2021-30185? Upgrade indico to 2.3.4 or later.