CVE-2026-27492
Lettermint ≤ 1.5.1
Raw vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:NCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-27492 is a medium-severity Exposure of Data Element to Wrong Session (CWE-488) vulnerability in Lettermint Lettermint. Its CVSS base score is 4.7 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Web Session Cookie (T1550.004); ranked at the 6th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
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-2026-7708
Vulnerability Data
Lettermint Node.js SDK is the official Node.js SDK for Lettermint. In versions 1.5.0 and below, email properties (such as to, subject, html, text, and attachments) are not reset between sends when a single client instance is reused across multiple .send()…
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calls. This can cause properties from a previous send to leak into a subsequent one, potentially delivering content or recipient addresses to unintended parties. Applications sending emails to different recipients in sequence — such as transactional flows like password resets or notifications — are affected. This issue has been fixed in version 1.5.1.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
AC-3 enforces access decisions that can be scoped to the correct session context.
AC-4 controls information flows between entities, reducing cross-session leakage.
SC-4 directly stops unintended transfer of data through shared resources that different sessions may access.
SC-39 isolates execution domains so one session cannot reach another's state or data.
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.
Enforcing authorization policies and least privilege can prevent cross-session data exposure when session separation is treated as an access rule.
Protecting data-in-use directly addresses runtime leakage of session data to unauthorized contexts.
Logical access controls and segmentation can be applied to isolate session state within applications or environments.
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 the weakness but does not itself implement the preventive control.
Secure development lifecycle practices include session-management controls that prevent exposure of data to the wrong session.
Application security requirements explicitly call for proper session isolation and state management.
Secure system architecture principles require isolation of session state to avoid cross-session data leakage.
Secure coding standards mandate correct session handling to prevent exposure of data elements to the wrong session.
Information access restriction directly enforces session boundaries so data is not exposed to the wrong session.