CVE-2026-126615VulnerabilityPublished 11 Nov 2026

The sign-in of Progressive Robot hMailServer 6.2.22-pre2 through 6.3.7 takes for an account names that are not its

Source GCVE Database

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Authoritative record:CVE-2026-126615· Medium 5.3

Not known to be exploited · CVSS 5.3 Medium.

Data as of 11 Nov 2026, 10:05 UTC

CVSS 3.1 base score

5.3Medium

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

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitLab)	CVSS 3.1	5.3

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
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: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
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 11 Nov 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 10 Nov 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.

ghsa-67h5-cmp2-p9hr

What to do

Affected software

Product	Affected	Fixed in
Progressive Robot LtdhMailServer	Affected >=6.2.22-pre2 <=6.3.7	Fixed in–
GitHubhmailserver/hmailserver`pkg:github/hmailserver/hmailserver`Other threats	Affected >=6.2.22-pre2 <=6.3.7	Fixed in–

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

AI-suggested

Users should monitor vendor advisories for remediation updates. Until a fix is available, consider disabling or carefully configuring the per-name lockout and compromised-account hold features, and limit exposure of affected authentication protocols where possible. Avoid using database collations or configurations that cause multiple spellings of account names. Review and harden authentication mechanisms to reduce risk.

Description

hMailServer versions 6.2.22-pre2 through 6.3.7 have an authentication issue where account name comparisons by the database differ from the per-name lockout and compromised-account hold checks. This discrepancy allows remote unauthenticated attackers to bypass lockout thresholds by guessing passwords under different account name spellings. Additionally, accounts held for review can be accessed using alternate spellings with the correct password. The issue arises from how various databases handle case, accents, whitespace, and character width in account names, leading to multiple spellings of the same account with separate lockout thresholds.

Impact

An attacker can bypass the per-name lockout mechanism by attempting password guesses across multiple spellings of the same account name, effectively multiplying the allowed number of guesses and increasing the risk of password compromise. Additionally, accounts flagged as compromised and held can still be accessed using alternate spellings with the correct password, potentially allowing unauthorized access. This undermines the effectiveness of lockout and compromised-account protections, increasing the risk of unauthorized account access.

Summary

The vulnerability in Progressive Robot hMailServer versions 6.2.22-pre2 through 6.3.7 involves inconsistent handling of account name spellings between the database lookup and the per-name lockout and compromised-account hold mechanisms. The lockout and hold checks are applied to the client-supplied account name after normalization (trimming, lowercasing, domain aliasing), but the database may find the account under different spellings due to collation and comparison rules varying by database backend (MySQL, MariaDB, SQL Server, PostgreSQL). This results in multiple distinct spellings of an account each having its own lockout threshold, allowing attackers to bypass lockout by guessing passwords across these variants. Furthermore, accounts marked as compromised and held can be accessed by signing in with alternate spellings and the correct password. The issue affects authentication over IMAP, POP3, SMTP AUTH, and optionally ManageSieve, REST API, and webmail. OAuth 2.0 tokens and other identity provider mappings are also affected. The vulnerability has a CVSS 3.1 base score of 5.3 (medium severity).

CWE-289Authentication Bypass by Alternate Name (opens in a new tab)
Base weaknessOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
The product performs authentication based on the name of a resource being accessed, or the name of the actor performing the access, but it does not properly check all possible names for that resource or actor.
Architecture and Design · Input Validation
Avoid making decisions based on names of resources (e.g. files) if those resources can have alternate names.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Implementation · Input Validation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174).
OWASP Cheat Sheets
OWASP Authentication (opens in a new tab)
OWASP ASVS 4.0.3
V2.8.5 (opens in a new tab)
V2.8.4 (opens in a new tab)
V9.2.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 11 Nov 2026, 10:05 UTC

WeaknessesCWE-289

Technical details

References

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