High severity · published Apr 1, 2021
CVE-2021-20235
There's a flaw in the zeromq server in versions before 4.3.3 in src/decoder_allocators.hpp
8.1
CVSS
43.9%
EPSS
No
On KEV
Description
There's a flaw in the zeromq server in versions before 4.3.3 in src/decoder_allocators.hpp. The decoder static allocator could have its sized changed, but the buffer would remain the same as it is a static buffer. A remote, unauthenticated attacker who sends a crafted request to the zeromq server could trigger a buffer overflow WRITE of arbitrary data if CURVE/ZAP authentication is not enabled. The greatest impact of this flaw is to application availability, data integrity, and confidentiality.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)43.9% · higher than 99% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LI
Libzmq · Zeromq
4.2.0 before 4.3.3 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-20235
CVE.org
https://www.cve.org/CVERecord?id=CVE-2021-20235
Issue Tracking
https://bugzilla.redhat.com/show_bug.cgi?id=1921983
Patch
https://github.com/zeromq/libzmq/security/advisories/GHSA-fc3w-qxf5-7hp6
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