Is CVE-2021-27905 being actively exploited?

It is not currently in CISA's KEV catalog. Its EPSS exploitation probability is 93%.

What products does CVE-2021-27905 affect?

Tracked products affected include Apache Solr. Check the version you run to see whether it is affected.

How do I fix CVE-2021-27905?

Apply the vendor fix promptly. Upgrade affected products to a fixed version.

CVE-2021-27905

Q: What is CVE-2021-27905?

CVE-2021-27905 is a critical-severity software vulnerability (Server-side request forgery (SSRF)) with a CVSS score of 9.8. 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 inde

CRITICAL severity · CVSS 9.8 · Server-side request forgery (SSRF)

9.8CVSS CRITICAL

Summary

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.

Impact & exploitability

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionNone

Confidentiality impactHigh

Integrity impactHigh

Availability impactHigh

Exploit probability (EPSS)93%

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products we track (1)

Apache Solr

Recommendation

Apply the vendor fix promptly. Open any affected product above for its exact safe version.

CVE-2021-27905

Summary

Impact & exploitability

Affected products we track (1)

Recommendation

Additional information