CVE-2026-49952 | Discuz! X5.0 releases 20260320 through 20260501 contains an … | CVSS 9.1 CRITICAL

Description

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.

Metadata

CVE ID: CVE-2026-49952
State: PUBLISHED
Assigner: VulnCheck
Reserved: 2026-06-02 16:30 UTC
Published: 2026-06-15 18:43 UTC
Last updated: 2026-06-15 19:59 UTC
Primary CWE: CWE-323
Reusing a Nonce, Key Pair in Encryption
Vendor / Product: Discuz! / Discuz! X5.0
Sources: cve.org · NVD

Severity & Metrics

9.1 CRITICAL CVSS 3.1

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

SSVC — CISA Coordinator

Exploitation: PoC
Automatable: yes
Tech. Impact: total

Affected products (1)

Vendor	Product	Platform	Versions
Discuz!	Discuz! X5.0	—	20260320 ≤ 20260501

Weakness (CWE)

CWE	Source	Description
CWE-323	cna	Reusing a Nonce, Key Pair in Encryption

CVSS scores (2)

Score	Severity	Version	Source	Vector
9.3	CRITICAL	4.0	cna	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
9.1	CRITICAL	3.1	cna	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

References (4)