# CVE-2026-10143: kafka-python prior to 2.3.2 DoS via SCRAM Iteration Count in scram.py

Status: published. Published: 2026-06-10. Updated: 2026-11-08.

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.

## Remediation

- fix: RHSA-2026:33683: Red Hat Quay 3.10

RHSA-2026:30076: Red Hat Quay 3.12

RHSA-2026:42796: Red Hat Quay 3.15

RHSA-2026:41066: Red Hat Quay 3.16

RHSA-2026:28571: Red Hat Quay 3.9 (source: ADP: redhat-SADP)
- workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability. (source: ADP: redhat-SADP)
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/dpkp/kafka-python/pull/3019
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/dpkp/kafka-python/commit/6e4831444f972d169cdd11f5c8d50333cea3f19b
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/dpkp/kafka-python/pull/3026

## Affected products and versions

- Dana Powers / kafka-python (kafka-python): ≥ 0; < 2.3.2 (affected, git). Source: CNA: VulnCheck
- Red Hat / Red Hat Quay 3.10 (quay/quay-rhel8): ≥ 1782487717; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Quay 3.12 (quay/quay-rhel8): ≥ 1781937357; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Quay 3.15 (quay/quay-rhel8): ≥ 1784351966; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Quay 3.16 (quay/quay-rhel9): ≥ 1783955846; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Quay 3.9 (quay/quay-rhel8): ≥ 1781878070; < * (unaffected, rpm). Source: ADP: redhat-SADP

## Severity and prioritization

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H; source: CNA: VulnCheck

- CVSS 4.0: 8.7 (high); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H; source: ADP: redhat-SADP

- CISA KEV: No listing in collected sources

- EPSS: 0.52% as of 2026-11-08; percentile 44.25%

- SSVC: exploitation none; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-400, CWE-606

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/dpkp/kafka-python/pull/3019 (CNA: VulnCheck; issue-tracking, patch)

- https://github.com/dpkp/kafka-python/commit/6e4831444f972d169cdd11f5c8d50333cea3f19b (CNA: VulnCheck; patch)

- https://github.com/dpkp/kafka-python/pull/3026 (CNA: VulnCheck; issue-tracking, patch)

- https://www.vulncheck.com/advisories/kafka-python-prior-to-dos-via-scram-iteration-count-in-scram-py (CNA: VulnCheck; third-party-advisory)

- https://access.redhat.com/security/cve/CVE-2026-10143 (ADP: redhat-SADP; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2487722 (ADP: redhat-SADP; issue-tracking, x_refsource_REDHAT)

- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-10143.json (ADP: redhat-SADP; x_sadp-csaf-vex)

- https://access.redhat.com/errata/RHSA-2026:33683 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:30076 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:42796 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:41066 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:28571 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-10143; retrieved 2026-11-08; source updated 2026-11-08

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-10143; retrieved 2026-11-08; source updated Not reported

Revision: eb0fa356f1b7e1be2f196f6cf6766fd0b12a3f6500572cb118c24d40e4260bac

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