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Description

kafka-python prior to 2.3.2 contains a denial-of-service vulnerability in SCRAM authentication handling that allows a malicious or machine-in-the-middle broker to freeze the client event loop by supplying an excessively large iteration count. In scram.py, ScramClient.process_server_first_message() passes the broker-controlled SCRAM iteration count directly to hashlib.pbkdf2_hmac() without validation, blocking producer sends, consumer polls, admin operations, and heartbeats, which can cause consumer group eviction and repeated reconnect failures.

PUBLISHED Reserved 2026-05-29 | Published 2026-06-10 | Updated 2026-06-10 | Assigner VulnCheck




HIGH: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

HIGH: 8.7CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Problem types

CWE-400 Uncontrolled Resource Consumption

Product status

Default status
unknown

Any version before 2.3.2
affected

Credits

Katriel Moses finder

References

github.com/dpkp/kafka-python/pull/3019 technical-description

github.com/...ommit/6e4831444f972d169cdd11f5c8d50333cea3f19b patch

github.com/dpkp/kafka-python/pull/3026

www.vulncheck.com/...s-via-scram-iteration-count-in-scram-py third-party-advisory

cve.org (CVE-2026-10143)

nvd.nist.gov (CVE-2026-10143)

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