#VU66176 Out-of-bounds write in zeromq - CVE-2021-20235

Vulnerability identifier: #VU66176

Vulnerability risk: High

CVSSv4.0: 7.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2021-20235

CWE-ID: CWE-787

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
zeromq
Other software / Other software solutions

Vendor: ZeroMQ Project

Description

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to a boundary error in src/decoder_allocators.hpp. A remote attacker can send a specially crafted request to the zeromq server and trigger a buffer overflow write of arbitrary data if CURVE/ZAP authentication is not enabled.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

zeromq: 4.2.0 - 4.3.2

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External links
https://bugzilla.redhat.com/show_bug.cgi?id=1921983
https://github.com/zeromq/libzmq/security/advisories/GHSA-fc3w-qxf5-7hp6

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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.