CVE-2026-40687
Exim SPA Authentication Driver Uninitialized Memory Disclosure
Description
In Exim before 4.99.2, when the SPA authentication driver is used with an adversarial SPA resource, there can be an out-of-bounds write that crashes the connection instance, or erroneous data processing that divulges data from uninitialized heap memory.
INFO
Published Date :
April 30, 2026, 10:16 p.m.
Last Modified :
April 30, 2026, 10:16 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-40687
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | 8254265b-2729-46b6-b9e3-3dfca2d5bfca | ||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | MEDIUM | MITRE-CVE |
Solution
- Update Exim to version 4.99.2 or later.
- Review SPA authentication driver configuration.
- Implement input validation for SPA resources.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-40687.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-40687 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-40687
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-40687 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-40687 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by [email protected]
Apr. 30, 2026
Action Type Old Value New Value Added Description In Exim before 4.99.2, when the SPA authentication driver is used with an adversarial SPA resource, there can be an out-of-bounds write that crashes the connection instance, or erroneous data processing that divulges data from uninitialized heap memory. Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L Added CWE CWE-909 Added Reference https://code.exim.org/exim/exim/commit/68b963b9f75ca27b38e1c0f8c87037990199f505 Added Reference https://exim.org/static/doc/security/CVE-2025-40687.txt Added Reference https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40687.assessment Added Reference https://www.openwall.com/lists/oss-security/2026/04/30/21