# CVE-2026-40542

## Summary

- **CVE ID:** CVE-2026-40542
- **Severity:** HIGH
- **CVSS Score:** 7.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L)
- **CWE:** CWE-304
- **Published:** Apr 22, 2026
- **Last Modified:** Sep 9, 2026

## Description

Missing critical step in authentication in Apache HttpClient 5.6 allows an attacker to cause the client to accept SCRAM-SHA-256 authentication without proper mutual authentication verification. Users are recommended to upgrade to version 5.6.1, which fixes this issue.

## Affected Products

- Apache Software Foundation — Apache HttpClient (5.6)

## References

- [CNA](https://lists.apache.org/thread/tfmgv86xr0z1y096vs3z0y315t1v3o97)
- [CVE](http://www.openwall.com/lists/oss-security/2026/04/22/5)
- [redhat-SADP](https://access.redhat.com/security/cve/CVE-2026-40542)
- [redhat-SADP](https://bugzilla.redhat.com/show_bug.cgi?id=2460518)
- [redhat-SADP](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40542.json)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:60247)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:60239)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:60251)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:60246)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:60250)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:60259)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:60254)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:60249)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:60248)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:60252)
- [redhat-SADP](https://access.redhat.com/errata/RHSA-2026:60256)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.56%
- **EPSS Percentile:** 44.6

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._