CVE-2026-126609 (GCVE-0-2026-126609)
Vulnerability from cvelistv5 – Published: 2026-11-11 08:30 – Updated: 2026-11-11 08:30
VLAI
EPSS
VEX
Title
Improper Certificate Validation in hMailServer
Summary
Progressive Robot hMailServer 6.2.25 through 6.3.7 on Windows, with a PostgreSQL database, the connection's sslmode require, verify-ca or verify-full, and a root certificate file named by PostgreSQLSslRootCert (from 6.2.25) or, with TlsMode=verify-full and neither PostgreSQL key set, by TlsCaFile (from 6.3.4), hands the file's name to libpq as bytes in the system's ANSI code page (up to 6.3.5 as Latin-1 bytes, which on code page 1252 are the code page's own for U+00A0 to U+00FF), and libpq looks for the file by those bytes and then hands the same bytes to OpenSSL, whose file opening on Windows reads a name as UTF-8 first and opens the file at that reading when one is there. When every byte of the name outside ASCII also reads as UTF-8 - for example U+00C3 U+00A9, the bytes C3 A9 on code page 1252, which are U+00E9 in UTF-8 - the database server's certificate was checked against the file at that other name whenever one was there, which allows a local attacker who can create that file but cannot change the configured one, as any user can by default beside a file an administrator keeps under ProgramData, or beside a folder directly under the system drive's root whose permissions the administrator restricted, and who can intercept the connection to the database server or stand in for it, to have hMailServer trust a certificate authority of the attacker's own and read and modify the traffic between hMailServer and its database, the database password included; the file alone, holding no authority that issued the database server's certificate, stops hMailServer from connecting to its database. The same applies in 6.3.4 through 6.3.7 to TlsCaFile when an Oracle MySQL client library has been put in place of the bundled MariaDB Connector/C, since that client opens the file through OpenSSL in the same way; the bundled MariaDB Connector/C opens the file in the code page and is not affected, and neither are the Linux builds. The configuration is not the default: by default no root certificate file is named.
Severity
7.5 (High)
CWE
- CWE-295 - Improper Certificate Validation
Assigner
References
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Progressive Robot Ltd | hMailServer |
Affected:
6.2.25 , ≤ 6.3.7
(semver)
|
guessed |
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "hMailServer",
"repo": "https://gitlab.com/hmailserver/hmailserver",
"vendor": "Progressive Robot Ltd",
"versions": [
{
"lessThanOrEqual": "6.3.7",
"status": "affected",
"version": "6.2.25",
"versionType": "semver"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Found by the hMailServer project (Progressive Robot Ltd)"
}
],
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{
"lang": "en",
"value": "Progressive Robot hMailServer 6.2.25 through 6.3.7 on Windows, with a PostgreSQL database, the connection\u0027s sslmode require, verify-ca or verify-full, and a root certificate file named by PostgreSQLSslRootCert (from 6.2.25) or, with TlsMode=verify-full and neither PostgreSQL key set, by TlsCaFile (from 6.3.4), hands the file\u0027s name to libpq as bytes in the system\u0027s ANSI code page (up to 6.3.5 as Latin-1 bytes, which on code page 1252 are the code page\u0027s own for U+00A0 to U+00FF), and libpq looks for the file by those bytes and then hands the same bytes to OpenSSL, whose file opening on Windows reads a name as UTF-8 first and opens the file at that reading when one is there. When every byte of the name outside ASCII also reads as UTF-8 - for example U+00C3 U+00A9, the bytes C3 A9 on code page 1252, which are U+00E9 in UTF-8 - the database server\u0027s certificate was checked against the file at that other name whenever one was there, which allows a local attacker who can create that file but cannot change the configured one, as any user can by default beside a file an administrator keeps under ProgramData, or beside a folder directly under the system drive\u0027s root whose permissions the administrator restricted, and who can intercept the connection to the database server or stand in for it, to have hMailServer trust a certificate authority of the attacker\u0027s own and read and modify the traffic between hMailServer and its database, the database password included; the file alone, holding no authority that issued the database server\u0027s certificate, stops hMailServer from connecting to its database. The same applies in 6.3.4 through 6.3.7 to TlsCaFile when an Oracle MySQL client library has been put in place of the bundled MariaDB Connector/C, since that client opens the file through OpenSSL in the same way; the bundled MariaDB Connector/C opens the file in the code page and is not affected, and neither are the Linux builds. The configuration is not the default: by default no root certificate file is named."
}
],
"metrics": [
{
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"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 7.5,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
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"problemTypes": [
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"descriptions": [
{
"cweId": "CWE-295",
"description": "CWE-295: Improper Certificate Validation",
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],
"providerMetadata": {
"dateUpdated": "2026-11-11T08:30:17.425Z",
"orgId": "ceab7361-8a18-47b1-92ba-4d7d25f6715a",
"shortName": "GitLab"
},
"references": [
{
"url": "https://gitlab.com/hmailserver/hmailserver/-/work_items/114"
},
{
"url": "https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.8"
}
],
"solutions": [
{
"lang": "en",
"value": "Upgrade to hMailServer 6.3.8, which on Windows refuses before connecting, with HM7534 in the error log, a root certificate file name whose bytes in the code page outside ASCII also read as UTF-8, for PostgreSQLSslRootCert and TlsCaFile alike and whichever database client is loaded, and hands an Oracle MySQL client the name in UTF-8, which names the same file. Until then, name the root certificate file by a path in ASCII alone, which reads as the same name in the code page and in UTF-8 and which every affected version hands over unchanged; where a name outside ASCII must stay, make sure no one else can create the file or folder that the name\u0027s UTF-8 reading names."
}
],
"title": "Improper Certificate Validation in hMailServer"
}
},
"cveMetadata": {
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"datePublished": "2026-11-11T08:30:17.425Z",
"dateReserved": "2026-11-11T08:04:24.373Z",
"dateUpdated": "2026-11-11T08:30:17.425Z",
"state": "PUBLISHED"
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"dataVersion": "5.2",
"vulnerability-lookup:meta": {
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"date": "2026-11-11",
"epss": "0.00172",
"percentile": "0.0669"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "hMailServer",
"repo": "https://gitlab.com/hmailserver/hmailserver",
"vendor": "Progressive Robot Ltd",
"versions": [
{
"lessThanOrEqual": "6.3.7",
"status": "affected",
"version": "6.2.25",
"versionType": "semver"
}
]
}
],
"source": "cve@gitlab.com"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Progressive Robot hMailServer 6.2.25 through 6.3.7 on Windows, with a PostgreSQL database, the connection\u0027s sslmode require, verify-ca or verify-full, and a root certificate file named by PostgreSQLSslRootCert (from 6.2.25) or, with TlsMode=verify-full and neither PostgreSQL key set, by TlsCaFile (from 6.3.4), hands the file\u0027s name to libpq as bytes in the system\u0027s ANSI code page (up to 6.3.5 as Latin-1 bytes, which on code page 1252 are the code page\u0027s own for U+00A0 to U+00FF), and libpq looks for the file by those bytes and then hands the same bytes to OpenSSL, whose file opening on Windows reads a name as UTF-8 first and opens the file at that reading when one is there. When every byte of the name outside ASCII also reads as UTF-8 - for example U+00C3 U+00A9, the bytes C3 A9 on code page 1252, which are U+00E9 in UTF-8 - the database server\u0027s certificate was checked against the file at that other name whenever one was there, which allows a local attacker who can create that file but cannot change the configured one, as any user can by default beside a file an administrator keeps under ProgramData, or beside a folder directly under the system drive\u0027s root whose permissions the administrator restricted, and who can intercept the connection to the database server or stand in for it, to have hMailServer trust a certificate authority of the attacker\u0027s own and read and modify the traffic between hMailServer and its database, the database password included; the file alone, holding no authority that issued the database server\u0027s certificate, stops hMailServer from connecting to its database. The same applies in 6.3.4 through 6.3.7 to TlsCaFile when an Oracle MySQL client library has been put in place of the bundled MariaDB Connector/C, since that client opens the file through OpenSSL in the same way; the bundled MariaDB Connector/C opens the file in the code page and is not affected, and neither are the Linux builds. The configuration is not the default: by default no root certificate file is named."
}
],
"id": "CVE-2026-126609",
"lastModified": "2026-11-11T09:17:12.687",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "HIGH",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 7.5,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
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"source": "cve@gitlab.com",
"type": "Secondary"
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},
"published": "2026-11-11T09:17:12.687",
"references": [
{
"source": "cve@gitlab.com",
"url": "https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.8"
},
{
"source": "cve@gitlab.com",
"url": "https://gitlab.com/hmailserver/hmailserver/-/work_items/114"
}
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"weaknesses": [
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"value": "CWE-295"
}
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"source": "cve@gitlab.com",
"type": "Primary"
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]
}
}
}
}
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Browse all ATT&CK techniques and the vulnerabilities related to each.
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