#VU52713 Improper access control in Apache Tapestry - CVE-2021-27850

Vulnerability identifier: #VU52713

Vulnerability risk: Medium

CVSSv4.0: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:A/U:Green]

CVE-ID: CVE-2021-27850

CWE-ID: CWE-284

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
Apache Tapestry
Web applications / Modules and components for CMS

Vendor: Apache Foundation

Description

The vulnerability allows a remote attacker to gain unauthorized access to otherwise restricted functionality.

The vulnerability exists due to improper access restrictions. A remote attacker can bypass implemented security restrictions and download the "AppModule.class" file and obtain the HMAC secret key.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Apache Tapestry: 5.4 - 5.7.0

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External links
https://lists.apache.org/thread.html/r237ff7f286bda31682c254550c1ebf92b0ec61329b32fbeb2d1c8751%40%3Cusers.tapestry.apache.org%3E
https://www.openwall.com/lists/oss-security/2021/04/15/1

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, a fully functional exploit for this vulnerability is available.