CVE-2021-32623— Opencast vulnerable to billion laughs attack (XML bomb)
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I. Basic Information for CVE-2021-32623
Vulnerability Information
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Vulnerability Title
Opencast vulnerable to billion laughs attack (XML bomb)
Source: CVE Program / CVE List V5
Vulnerability Description
Opencast is a free and open source solution for automated video capture and distribution. Versions of Opencast prior to 9.6 are vulnerable to the billion laughs attack, which allows an attacker to easily execute a (seemingly permanent) denial of service attack, essentially taking down Opencast using a single HTTP request. To exploit this, users need to have ingest privileges, limiting the group of potential attackers The problem has been fixed in Opencast 9.6. There is no known workaround for this issue.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
DTD中递归实体索引的不恰当限制(XML实体扩展)
Source: CVE Program / CVE List V5
Vulnerability Title
Opencast 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Opencast是Opencast组织的一款用于大规模自动视频捕获，管理和分发的直播视频支撑软件。 Opencast 9.6版本及之前版本存在安全漏洞，该漏洞源于Opencast很容易受到the billion laughs attack（一种DoS攻击）。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2021-32623
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Patches & Fixes for CVE-2021-32623 (1)
Vendor Advisories for CVE-2021-32623 (1)
- https://github.com/opencast/opencast/security/advisories/GHSA-9gwx-9cwp-5c2mx_refsource_CONFIRM
IV. Related Vulnerabilities
Same product: opencast
- CVE-2025-61906
Opencast's editor accidentally publishes videos/overwrites p - CVE-2025-61788
Opencast Paella Player 7 vulnerable to Cross-Site-Scripting - CVE-2025-55202
Opencast has a partial path traversal vulnerability in UI co - CVE-2025-54380
Opencast still publishes global system account credentials - CVE-2024-52797
Searching Opencast may cause a denial of service
Same vendor: opencast
- CVE-2025-61906
Opencast's editor accidentally publishes videos/overwrites p - CVE-2025-61788
Opencast Paella Player 7 vulnerable to Cross-Site-Scripting - CVE-2025-55202
Opencast has a partial path traversal vulnerability in UI co - CVE-2025-54380
Opencast still publishes global system account credentials - CVE-2024-52797
Searching Opencast may cause a denial of service
Same weakness: CWE-776
- CVE-2026-14865
XXE Denial of Service via RadLayoutBuilder Client State in T - CVE-2026-14979
IBM Engineering Lifecycle Management - Jazz Foundation is vu - CVE-2026-45304
Symfony: YAML Parser Exponential Memory Allocation via Recur - CVE-2026-12993
Apicurio/apicurio-registry: apicurio-registry: xml entity-ex - CVE-2026-44020
Docling: Unsafe XML Entity Expansion in USPTO Patent Backend
V. Comments for CVE-2021-32623
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