{"document":{"category":"csaf_vex","csaf_version":"2.0","title":"CVE-2026-49952: Discuz! X5.0 Authentication Bypass via dbbak.php Encryption Oracle","publisher":{"category":"vendor","name":"HarborGuard Database","namespace":"https://database.harborguard.co"},"tracking":{"id":"CVE-2026-49952","status":"final","version":"1","initial_release_date":"2026-06-15T18:43:21.990Z","current_release_date":"2026-06-15T19:59:18.533Z","revision_history":[{"date":"2026-06-15T18:43:21.990Z","number":"1","summary":"Initial machine-readable export from HarborGuard."}]},"distribution":{"tlp":{"label":"WHITE"},"text":"Public CVE data; freely redistributable."},"notes":[{"category":"description","text":"Discuz! X5.0 releases 20260320 through 20260501 contains an authentication bypass vulnerability that allows unauthenticated remote attackers to gain unauthorized access to database backup and restore functionality by exploiting a shared cryptographic key between UCenter integration and the database backup API exposed by dbbak.php. Attackers can inject a crafted payload through the username parameter during login to abuse the encryption oracle in logging_ctl::logging_more(), obtain a legitimately signed token, and use it to bypass authorization for database export and import operations, with the additional ability to trigger a race condition to impersonate arbitrary users.","title":"CVE description"}],"references":[{"category":"self","summary":"CVE-2026-49952 on HarborGuard Database","url":"https://database.harborguard.co/cve/CVE-2026-49952"},{"category":"external","summary":"CVE Record","url":"https://www.cve.org/CVERecord?id=CVE-2026-49952"},{"category":"external","summary":"karmainsecurity.com","url":"https://karmainsecurity.com/KIS-2026-09"},{"category":"external","summary":"karmainsecurity.com","url":"https://karmainsecurity.com/chaining-bugs-in-discuz-from-race-condition-to-rce"},{"category":"external","summary":"gitee.com","url":"https://gitee.com/Discuz/DiscuzX/commit/9962dad52c4c6999dabaf91ecd70377c680ff3c6"},{"category":"external","summary":"vulncheck.com","url":"https://www.vulncheck.com/advisories/discuz-x5-0-authentication-bypass-via-dbbak-php-encryption-oracle"}]},"product_tree":{"branches":[{"category":"vendor","name":"Discuz!","branches":[{"category":"product_name","name":"Discuz! X5.0","branches":[{"category":"product_version_range","name":">=20260320 <=20260501","product":{"name":"Discuz! Discuz! X5.0 >=20260320 <=20260501","product_id":"CSAFPID-1","product_identification_helper":{"cpe":"cpe:2.3:a:discuz\\!:discuz\\!_x5.0:*:*:*:*:*:*:*:*"}}}]}]}]},"vulnerabilities":[{"cve":"CVE-2026-49952","title":"Discuz! X5.0 Authentication Bypass via dbbak.php Encryption Oracle","notes":[{"category":"description","text":"Discuz! X5.0 releases 20260320 through 20260501 contains an authentication bypass vulnerability that allows unauthenticated remote attackers to gain unauthorized access to database backup and restore functionality by exploiting a shared cryptographic key between UCenter integration and the database backup API exposed by dbbak.php. Attackers can inject a crafted payload through the username parameter during login to abuse the encryption oracle in logging_ctl::logging_more(), obtain a legitimately signed token, and use it to bypass authorization for database export and import operations, with the additional ability to trigger a race condition to impersonate arbitrary users.","title":"CVE description"}],"product_status":{"known_affected":["CSAFPID-1"]},"scores":[{"cvss_v4":{"version":"4.0","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","baseScore":9.3,"baseSeverity":"CRITICAL"},"products":["CSAFPID-1"]}],"remediations":[{"category":"none_available","details":"No fixed version is published yet. Monitor the upstream advisory.","product_ids":["CSAFPID-1"]}]}]}