CVE-2021-27905

SSRF vulnerability with the Replication handler

CRITICAL
9.8
CVSS Score
Published: April 13, 2021 at 06:35 AM UTC
Updated: June 17, 2026 at 03:45 AM UTC
1 product affected across 1 vendorSolr

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Severity
CRITICAL9.8
Exploit prediction
EPSS 93%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 8.8.2Apache Solr ≤ v < 8.8.2
Affected range stops below 8.8.2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-918

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