CVE-2026-22689
Axllent Mailpit ≤ 1.28.2
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:NSummary
CVE-2026-22689 is a medium-severity Missing Origin Validation in WebSockets (CWE-1385) vulnerability in Axllent Mailpit. Its CVSS base score is 6.5 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Browser Session Hijacking (T1185); ranked at the 12th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and AC-4 (Information Flow Enforcement) — see the control section below for these in your framework.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-1872
Vulnerability Data
Mailpit is an email testing tool and API for developers. Prior to version 1.28.2, the Mailpit WebSocket server is configured to accept connections from any origin. This lack of Origin header validation introduces a Cross-Site WebSocket Hijacking (CSWSH) vulnerability. An…
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attacker can host a malicious website that, when visited by a developer running Mailpit locally, establishes a WebSocket connection to the victim's Mailpit instance (default ws://localhost:8025). This allows the attacker to intercept sensitive data such as email contents, headers, and server statistics in real-time. This issue has been patched in version 1.28.2.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V4.4.2
Mitigating Controls (NIST 800-53 r5) AI
Enforces approved authorizations on logical access, which can include origin checks before accepting WebSocket connections.
Enforces information flow policies that can require validation of communication origins at system boundaries.
Protects authenticity of communications sessions, which origin validation helps ensure for WebSocket handshakes.
Monitors and controls communications at external interfaces, directly supporting origin validation for inbound WebSocket traffic.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require origin validation for WebSocket endpoints.
Origin validation is a required step when authenticating WebSocket connection requests.
Enforcing authorization policy on incoming connections can require origin checks.
Network-level controls that block unauthorized logical access can mitigate missing origin checks.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect missing origin validation in WebSocket implementations.
Network security controls can enforce origin validation and restrict WebSocket connections to trusted sources.
Secure configuration of network services can include origin checks for WebSocket endpoints.
Application security requirements can mandate origin validation for WebSocket communications.
Secure architecture principles can require proper origin validation mechanisms in WebSocket implementations.
Secure coding standards can explicitly require origin validation for WebSocket connections.