CVE-2026-40684
Medium
Description
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.
SeverityMedium
CVSS5.9
Exploit probability—
Product
Exim
PublishedApr 30, 2026
First seenApr 30, 2026
Weakness typeCWE-684CWE-684
How to fix
Update
- exim exim4.99.2 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| exim exim | v < 4.99.2 | 4.99.2 |
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