CVE-2026-40193 | Maddy Mail Server: LDAP Filter Injection via Unsanitized Username

Exp

maddy is a composable, all-in-one mail server. Versions prior to 0.9.3 contain an LDAP injection vulnerability in the auth.ldap module where user-supplied usernames are interpolated into LDAP search filters and DN strings via strings.ReplaceAll() without any LDAP filter escaping, despite the go-ldap/ldap/v3 library's ldap.EscapeFilter() function being available in the same import. This affects three code paths: the Lookup() filter, the AuthPlain() DN template, and the AuthPlain() filter. An attacker with network access to the SMTP submission or IMAP interface can inject arbitrary LDAP filter expressions through the username field in AUTH PLAIN or LOGIN commands. This enables identity spoofing by manipulating filter results to authenticate as another user, LDAP directory enumeration via wildcard filters, and blind extraction of LDAP attribute values using authentication responses as a boolean oracle or via timing side-channels between the two distinct failure paths. This issue has been fixed in version 0.9.3.

Published: 2026-04-16 Last update: 2026-04-22 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-40193 is rated Exploit Available (54/100): CVSS High severity, with low exploitation likelihood (EPSS 0.06%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

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

Public exploit references (Exploit-DB) for CVE-2026-40193

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-40193

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 2026-05-27 0.03% 0.06% +0.02%
2 2026-04-21 0.06% 0.03% -0.03%
3 2026-04-16 — 0.06% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-40193

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.2 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N 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:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 4.2 [email protected]

Weakness enumeration for CVE-2026-40193

GitHub Security Advisory for CVE-2026-40193

GHSA-5835-4gvc-32pc · Severity: high · Ecosystem: go — Maddy Mail Server has an LDAP Filter Injection via Unsanitized Username

OS Trackers for CVE-2026-40193

vendor priority summary link
alpine — CVE-2026-40193: 1 source package rows (maddy); 2 state rows across 2 repos (3.23-community, edge-community); fixed 2, open 0. https://security.alpinelinux.org/vuln/CVE-2026-40193

Affected software / configurations for CVE-2026-40193

Vendor Product Version Raw CPE
maddy_project maddy < 0.9.3 cpe:2.3:a:maddy_project:maddy:*:*:*:*:*:*:*:*

References for CVE-2026-40193

cvelogic Threat Intelligence