Exim: Security Vulnerabilities
In Exim before 4.99.2, on systems using musl libc (not glibc), an attacker can crash the connection instance when malformed DNS data is present in PTR records. This is caused by a dn_expand oddity in octal printing.
CVSS Score
5.9
EPSS Score
0.001
Published
2026-04-30
In Exim before 4.99.2, when JSON lookup is enabled, an out-of-bounds heap write can occur when a JSON operator encounters malformed JSON in an untrusted header, because of an incorrect implementation of \ skipping.
CVSS Score
6.5
EPSS Score
0.001
Published
2026-04-30
In Exim before 4.99.2, when utf8 operators are enabled, there is an out-of-bounds read if large UTF-8 trailing characters are present (malformed UTF-8 header data). Information might be divulged within an error message produced during handling of an unrelated e-mail message.
CVSS Score
3.7
EPSS Score
0.0
Published
2026-04-30
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.
CVSS Score
4.8
EPSS Score
0.001
Published
2026-04-30
Exim before 4.99.1, with certain non-default rate-limit configurations, allows a remote heap-based buffer overflow because database records are cast directly to internal structures without validation.
CVSS Score
7.0
EPSS Score
0.001
Published
2025-12-14
A use-after-free in Exim 4.96 through 4.98.1 could allow users (with command-line access) to escalate privileges.
CVSS Score
8.1
EPSS Score
0.0
Published
2025-03-28
Exim 4.98 before 4.98.1, when SQLite hints and ETRN serialization are used, allows remote SQL injection. (Resolving SQL injection requires an update to 4.99.1 in certain non-default rate-limit configurations.)
CVSS Score
7.5
EPSS Score
0.751
Published
2025-02-21
Exim through 4.97.1 misparses a multiline RFC 2231 header filename, and thus remote attackers can bypass a $mime_filename extension-blocking protection mechanism, and potentially deliver executable attachments to the mailboxes of end users.
CVSS Score
5.4
EPSS Score
0.603
Published
2024-07-04
Exim AUTH Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Exim. Authentication is not required to exploit this vulnerability.
The specific flaw exists within the smtp service, which listens on TCP port 25 by default. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of a buffer. An attacker can leverage this vulnerability to execute code in the context of the service account.
. Was ZDI-CAN-17434.
CVSS Score
9.8
EPSS Score
0.707
Published
2024-05-03
Exim SMTP Challenge Stack-based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Exim. Authentication is not required to exploit this vulnerability.
The specific flaw exists within the handling of NTLM challenge requests. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a fixed-length stack-based buffer. An attacker can leverage this vulnerability to execute code in the context of the service account.
. Was ZDI-CAN-17515.
CVSS Score
8.1
EPSS Score
0.067
Published
2024-05-03
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