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    CVE-2026-49953

    Discuz! X5.0 releases 20260320 through 20260610 contains a CAPTCHA bypass vulnerability that allows unauthenticated remote attackers to defeat challenge controls by exploiting limited complexity and predictable character sets in generated CAPTCHA images. Attackers can train a custom optical character recognition model against collected CAPTCHA samples to reliably predict challenge text, bypassing protections on login, registration, and other functionality from automated abuse.

    Published:Jun 15, 2026
    Last Modified:Jul 28, 2026
    EPS:Jun 15, 2026
    EPSS Score:0.00359
    CVSS Score:6.5

    Affected Products

    Vendor
    Discuz
    Product
    Discuzx

    Exploits

    No exploit reference

    Common Weakness Enumeration

    CWE-804 Guessable CAPTCHA

    Common Attack Pattern Enumeration and Classification (CAPEC)

    No CAPEC recorded yet

    Related CVEs

    CVE-2026-49954 (CVSS 8.6) — Discuz! X5.0 releases 20260320 through 20260610 contain a local file inclusion vulnerability that allows authe…
    CVE-2026-49952 (CVSS 9.3) — Discuz! X5.0 releases 20260320 through 20260501 contains an authentication bypass vulnerability that allows un…
    CVE-2024-30884 (CVSS 7.1) — Reflected Cross-Site Scripting (XSS) vulnerability in Discuz! version X3.4 20220811, allows remote attackers t…
    CVE-2022-45543 (CVSS 6.1) — Cross site scripting (XSS) vulnerability in DiscuzX 3.4 allows attackers to execute arbitrary code via the dat…
    CVE-2018-10298 (CVSS 5.4) — Discuz! DiscuzX through X3.4 has reflected XSS via forum.php?mod=post&action=newthread because data/template/1…
    CVE-2018-10297 (CVSS 5.4) — Discuz! DiscuzX through X3.4 has stored XSS via the portal.php?mod=portalcp&ac=article URI, related to mishand…
    CVE-2018-5375 (CVSS 6.1) — Discuz! DiscuzX X3.4 has XSS via the include\spacecp\spacecp_space.php appid parameter in a delete action.…
    CVE-2018-5377 (CVSS 9.8) — Discuz! DiscuzX X3.4 allows remote attackers to bypass intended access restrictions via the archiver\index.php…
    CVE-2018-5376 (CVSS 6.1) — Discuz! DiscuzX X3.4 has XSS via the include\spacecp\spacecp_upload.php op parameter.…
    CVE-2018-5331 (CVSS 5.4) — Discuz! DiscuzX X3.4 has XSS via the view parameter to include/space/space_poll.php, as demonstrated by a mod=…

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High