CVE-2026-40542 | Apache HttpClient: SCRAM-SHA-256 mutual authentication bypass may cause the client to accept authentication without proper mutual authentication verification

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.

Published: 2026-04-22 Last update: 2026-05-01 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-40542 is rated Moderate Risk (44.4/100): CVSS High severity, with low exploitation likelihood (EPSS 0.56%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-40542

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.05% 0.56% +0.51%
2 2026-05-24 0.04% 0.05% +0.01%
3 2026-05-22 — 0.04% —

Full EPSS history (5 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-40542

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.3 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 3.4 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2026-40542

GitHub Security Advisory for CVE-2026-40542

GHSA-v468-qcjx-r72w · Severity: high · Ecosystem: maven — Apache HttpClient accepts SCRAM-SHA-256 authentication without proper mutual authentication verification

OS Trackers for CVE-2026-40542

vendor priority summary link
debian unimportant CVE-2026-40542 unimportant priority: Debian including 1 source packages (httpcomponents-client), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2026-40542
suse high — https://www.suse.com/security/cve/CVE-2026-40542/
ubuntu medium CVE-2026-40542 medium priority: Ubuntu including 1 source packages (httpcomponents-client), 9 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): needs-triage 8, not-affected 1. https://ubuntu.com/security/CVE-2026-40542

Affected software / configurations for CVE-2026-40542

Vendor Product Version Raw CPE
apache httpclient 5.6 cpe:2.3:a:apache:httpclient:5.6:-:*:*:*:*:*:*

References for CVE-2026-40542

cvelogic Threat Intelligence