CVE-2021-27905
9.8 · CRITICALOverview
CVE-2021-27905 is a critical-severity vulnerability affecting apache solr. It was published on April 13, 2021 and has a CVSS 3.1 base score of 9.8 (CRITICAL).
This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
The ReplicationHandler (normally registered at "/replication" under a Solr core) in Apache Solr has a "masterUrl" (also "leaderUrl" alias) parameter that is used to designate another ReplicationHandler on another Solr core to replicate index data into the local core. To prevent a SSRF vulnerability, Solr ought to check these parameters against a similar configuration it uses for the "shards" parameter. Prior to this bug getting fixed, it did not. This problem affects essentially all Solr versions prior to it getting fixed in 8.8.2.
Remediation
Check the references section for vendor advisories and patches from apache. Update solr to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| apache | solr | >= 0, < 8.8.2 | Affected |
References
Frequently Asked Questions
What is CVE-2021-27905?
CVE-2021-27905 is a critical-severity vulnerability affecting apache solr. It was published on April 13, 2021 and has a CVSS 3.1 base score of 9.8 (CRITICAL).
How severe is CVE-2021-27905?
This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2021-27905?
Check the references section for vendor advisories and patches from apache. Update solr to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-27905?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-27905 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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