Apache HttpClient 5.6.0 SCRAM-SHA-256 Authentication critical step in authentication

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
7.1$0-$5k0.00

Summaryinfo

A vulnerability categorized as critical has been discovered in Apache HttpClient 5.6.0. Affected is an unknown function of the component SCRAM-SHA-256 Authentication. Executing a manipulation can lead to critical step in authentication. This vulnerability is handled as CVE-2026-40542. The attack can be executed remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Apache HttpClient 5.6.0. This vulnerability affects an unknown functionality of the component SCRAM-SHA-256 Authentication. The manipulation with an unknown input leads to a critical step in authentication vulnerability. The CWE definition for the vulnerability is CWE-304. The product implements an authentication technique, but it skips a step that weakens the technique. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The weakness was released by Rasmus Moorats. The advisory is available at lists.apache.org. This vulnerability was named CVE-2026-40542 since 04/14/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 07/02/2026). This issue was introduced with commit https://github.com/apache/httpcomponents-client/commit/5e73e17ae6c3886b8217d026a713303fd903ca4b

The vulnerability scanner Nessus provides a plugin with the ID 310832 (Linux Distros Unpatched Vulnerability : CVE-2026-40542), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.6.1 eliminates this vulnerability. Applying the patch 726eac2323d370435d8afca1e0540aa099927f18 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (310832). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.3
VulDB Meta Temp Score: 7.1

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

ADP CISA Base Score: 7.3
ADP CISA Vector: 🔒

CVSSv2info

AVACAuCIA
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Critical step in authentication
CWE: CWE-304
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-DayUnlockUnlockUnlockUnlock
TodayUnlockUnlockUnlockUnlock

Nessus ID: 310832
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-40542

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: HttpClient 5.6.1
Patch: 726eac2323d370435d8afca1e0540aa099927f18

Timelineinfo

04/14/2026 CVE reserved
04/22/2026 +8 days Advisory disclosed
04/22/2026 +0 days VulDB entry created
07/02/2026 +71 days VulDB entry last update

Sourcesinfo

Vendor: apache.org

Advisory: lists.apache.org
Researcher: Rasmus Moorats
Status: Confirmed

CVE: CVE-2026-40542 (🔒)
GCVE (CVE): GCVE-0-2026-40542
GCVE (VulDB): GCVE-100-358786

Entryinfo

Created: 04/22/2026 12:02
Updated: 07/02/2026 11:27
Changes: 04/22/2026 12:02 (55), 04/23/2026 05:54 (4), 04/29/2026 20:34 (2), 07/02/2026 11:27 (10)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Discussion

No comments yet. Languages: en.

Please log in to comment.

◂ PreviousOverviewNext ▸

Want to know what is going to be exploited?

We predict KEV entries!