$ cve CVE-2021-27905 JSON

CVE-2021-27905

9.8

CRITICAL · CVSS 3.1 · EPSS 93.1% (pctl 100)

Patch early

EPSS 93.1% — above the 10% action threshold.

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.

Scoring

CVSS	9.8 (CRITICAL, v3.1)
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS	93.05% — more likely to be exploited than 100% of all CVEs
Weakness	CWE-918
On CISA KEV	no
Public exploit	none known
Published	2021-04-13
Last modified	2026-06-17

Affected (1)

Vendor	Product
apache	solr

References

→ the Explorer · watch your stack · NVD