VulnerabilityPublished 21 Apr 2026

CVE-2026-40586: blueprintue-self-hosted-edition · Improper Restriction of Excessive Authentication Attempts

Affects blueprintue-self-hosted-editionSource CVE Database V5

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Not known to be exploited · CVSS 7.5 High : upgrade to 4.2.0 soon.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 30% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 4.2.0

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 21 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade blueprintue-self-hosted-edition and blueprintue/blueprintue-self-hosted-edition to 4.2.0.

Affected software

Product	Affected	Fixed in
blueprintueblueprintue-self-hosted-edition	Affected <4.2.0	Fixed in 4.2.0
GitHubblueprintue/blueprintue-self-hosted-edition`pkg:github/blueprintue/blueprintue-self-hosted-edition`Other threats	Affected <4.2.0	Fixed in 4.2.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade blueprintue-self-hosted-edition to version 4.2.0 or later, where this vulnerability is fixed by implementing proper throttling and rate limiting on authentication attempts. Patch status is confirmed fixed in 4.2.0.

Description

blueprintUE is a tool to help Unreal Engine developers. Prior to 4.2.0, the login form handler performs no throttling of any kind. Failed authentication attempts are processed at full network speed with no IP-based rate limiting, no per-account attempt counter, no temporary lockout, no progressive delay (Tarpit), and no CAPTCHA challenge. An attacker can submit an unlimited number of credential guesses. The password policy (10+ characters, mixed case, digit, special character) reduces the effective keyspace but does not prevent dictionary attacks, credential stuffing from breached databases, or targeted attacks against known users with predictable passwords. This vulnerability is fixed in 4.2.0.

Impact

An attacker can perform brute force or credential stuffing attacks without limitation, potentially leading to unauthorized access to user accounts. The vulnerability compromises confidentiality but does not affect integrity or availability. The lack of throttling increases the risk of account compromise, especially for users with reused or weak passwords despite the password policy.

Summary

The vulnerability in blueprintue-self-hosted-edition (before version 4.2.0) is an improper restriction of excessive authentication attempts (CWE-307). The login form handler does not implement any throttling mechanisms such as IP-based rate limiting, per-account attempt counters, temporary lockouts, progressive delays, or CAPTCHA challenges. This allows attackers to submit unlimited credential guesses rapidly. Although the password policy requires complex passwords, it does not prevent attacks leveraging breached credentials or predictable passwords. The issue is resolved in version 4.2.0.

CWE-307Improper Restriction of Excessive Authentication Attempts (opens in a new tab)
Base weaknessOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
The product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame.
Architecture and Design
Common protection mechanisms include: Disconnecting the user after a small number of failed attempts; Implementing a timeout; Locking out a targeted account; Requiring a computational task on the user's part.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
OWASP Cheat Sheets
Authentication (opens in a new tab)
Transport Layer Protection (opens in a new tab)
TLS Cipher String (opens in a new tab)
OWASP ASVS 4.0.3
V2.2.1 (opens in a new tab)
V2.8.5 (opens in a new tab)
V2.8.4 (opens in a new tab)
Attack patterns
Dictionary-based Password Attack (opens in a new tab)
Password Brute Forcing (opens in a new tab)
Password Spraying (opens in a new tab)
Credential Stuffing (opens in a new tab)
Use of Known Kerberos Credentials (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/blueprintue/blueprintue-self-hosted-edition/security/advisories/GHSA-m6c2-6p3h-8jv2 (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 21 Apr 2026, 17:31 UTC

WeaknessesCWE-307

Technical details

References

Community reviews

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