VulnerabilityModified
CVE-2026-40542
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.
HIGH 7.3EPSS 0.56%
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.56%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 7.3 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
- EPSS
- 0.56% probability · 45th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-304, CWE-325
- Affected
- apache/httpclient
- Source
- security@apache.org
References
- https://lists.apache.org/thread/tfmgv86xr0z1y096vs3z0y315t1v3o97Mailing List, Vendor Advisory
- http://www.openwall.com/lists/oss-security/2026/04/22/5Mailing List, Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:60239
- https://access.redhat.com/errata/RHSA-2026:60246
- https://access.redhat.com/errata/RHSA-2026:60247
- https://access.redhat.com/errata/RHSA-2026:60248
- https://access.redhat.com/errata/RHSA-2026:60249
- https://access.redhat.com/errata/RHSA-2026:60250
- https://access.redhat.com/errata/RHSA-2026:60251
- https://access.redhat.com/errata/RHSA-2026:60252
- https://access.redhat.com/errata/RHSA-2026:60254
- https://access.redhat.com/errata/RHSA-2026:60256
- https://access.redhat.com/errata/RHSA-2026:60259
- https://access.redhat.com/security/cve/CVE-2026-40542
- https://bugzilla.redhat.com/show_bug.cgi?id=2460518
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40542.json
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.