CVE-2026-40686
exim4: In Exim before 4.99.2, when utf8 operators are enabled, there is an out-of-bounds read if large UTF-8 trailing charac...
CVE-2026-40686 is fixed in 6 products on 1 platform, first by exim4 4.99.1-1ubuntu1.1, released April 29, 2026. It is not reported as exploited. Patch Radar priority: Routine.
Routine
CVSS
5.3
medium
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0025
15th percentile
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.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| exim4 · Debian 12.15 (bookworm) | 4.96-15+deb12u9 | DEBIAN-CVE-2026-40686 | May 15, 2026 |
| exim4 · Debian 13.5 (trixie) | 4.98.2-1+deb13u2 | DEBIAN-CVE-2026-40686 | May 15, 2026 |
| exim4 · Debian 14 | 4.99.2-1 | DEBIAN-CVE-2026-40686 | May 15, 2026 |
| exim4 · Ubuntu 20.04 LTS (focal) | 4.93-13ubuntu1.12+esm1 | exim4 4.93-13ubuntu1.12+esm1 | Jun 24, 2026 |
| exim4 · Ubuntu 22.04.1 LTS (jammy) | 4.95-4ubuntu2.7 | exim4 4.95-4ubuntu2.7 | May 15, 2026 |
| exim4 · Ubuntu 24.04.5 LTS (noble) | 4.97-4ubuntu4.4 | exim4 4.97-4ubuntu4.4 | May 15, 2026 |
| exim4 · Ubuntu 25.10 (questing) | 4.98.2-1ubuntu2.1 | exim4 4.98.2-1ubuntu2.1 | May 15, 2026 |
| exim4 · Ubuntu 26.04.1 LTS (resolute) | 4.99.1-1ubuntu1.1 | exim4 4.99.1-1ubuntu1.1 | Apr 29, 2026 |
| exim4-base · Ubuntu 20.04 LTS (focal) | 4.93-13ubuntu1.12+esm1 | exim4-base 4.93-13ubuntu1.12+esm1 | Jun 24, 2026 |
| exim4-base · Ubuntu 22.04.1 LTS (jammy) | 4.95-4ubuntu2.7 | exim4-base 4.95-4ubuntu2.7 | May 15, 2026 |
| exim4-base · Ubuntu 24.04.5 LTS (noble) | 4.97-4ubuntu4.4 | exim4-base 4.97-4ubuntu4.4 | May 15, 2026 |
| exim4-base · Ubuntu 25.10 (questing) | 4.98.2-1ubuntu2.1 | exim4-base 4.98.2-1ubuntu2.1 | May 15, 2026 |
| exim4-base · Ubuntu 26.04.1 LTS (resolute) | 4.99.1-1ubuntu1.1 | exim4-base 4.99.1-1ubuntu1.1 | Apr 29, 2026 |
| exim4-config · Ubuntu 20.04 LTS (focal) | 4.93-13ubuntu1.12+esm1 | exim4-config 4.93-13ubuntu1.12+esm1 | Jun 24, 2026 |
| exim4-config · Ubuntu 22.04.1 LTS (jammy) | 4.95-4ubuntu2.7 | exim4-config 4.95-4ubuntu2.7 | May 15, 2026 |
| exim4-config · Ubuntu 24.04.5 LTS (noble) | 4.97-4ubuntu4.4 | exim4-config 4.97-4ubuntu4.4 | May 15, 2026 |
| exim4-config · Ubuntu 25.10 (questing) | 4.98.2-1ubuntu2.1 | exim4-config 4.98.2-1ubuntu2.1 | May 15, 2026 |
| exim4-config · Ubuntu 26.04.1 LTS (resolute) | 4.99.1-1ubuntu1.1 | exim4-config 4.99.1-1ubuntu1.1 | Apr 29, 2026 |
| exim4-daemon-heavy · Ubuntu 20.04 LTS (focal) | 4.93-13ubuntu1.12+esm1 | exim4-daemon-heavy 4.93-13ubuntu1.12+esm1 | Jun 24, 2026 |
| exim4-daemon-heavy · Ubuntu 22.04.1 LTS (jammy) | 4.95-4ubuntu2.7 | exim4-daemon-heavy 4.95-4ubuntu2.7 | May 15, 2026 |
| exim4-daemon-heavy · Ubuntu 24.04.5 LTS (noble) | 4.97-4ubuntu4.4 | exim4-daemon-heavy 4.97-4ubuntu4.4 | May 15, 2026 |
| exim4-daemon-heavy · Ubuntu 25.10 (questing) | 4.98.2-1ubuntu2.1 | exim4-daemon-heavy 4.98.2-1ubuntu2.1 | May 15, 2026 |
| exim4-daemon-heavy · Ubuntu 26.04.1 LTS (resolute) | 4.99.1-1ubuntu1.1 | exim4-daemon-heavy 4.99.1-1ubuntu1.1 | Apr 29, 2026 |
| exim4-daemon-light · Ubuntu 20.04 LTS (focal) | 4.93-13ubuntu1.12+esm1 | exim4-daemon-light 4.93-13ubuntu1.12+esm1 | Jun 24, 2026 |
| exim4-daemon-light · Ubuntu 22.04.1 LTS (jammy) | 4.95-4ubuntu2.7 | exim4-daemon-light 4.95-4ubuntu2.7 | May 15, 2026 |
| exim4-daemon-light · Ubuntu 24.04.5 LTS (noble) | 4.97-4ubuntu4.4 | exim4-daemon-light 4.97-4ubuntu4.4 | May 15, 2026 |
| exim4-daemon-light · Ubuntu 25.10 (questing) | 4.98.2-1ubuntu2.1 | exim4-daemon-light 4.98.2-1ubuntu2.1 | May 15, 2026 |
| exim4-daemon-light · Ubuntu 26.04.1 LTS (resolute) | 4.99.1-1ubuntu1.1 | exim4-daemon-light 4.99.1-1ubuntu1.1 | Apr 29, 2026 |
| eximon4 · Ubuntu 20.04 LTS (focal) | 4.93-13ubuntu1.12+esm1 | eximon4 4.93-13ubuntu1.12+esm1 | Jun 24, 2026 |
| eximon4 · Ubuntu 22.04.1 LTS (jammy) | 4.95-4ubuntu2.7 | eximon4 4.95-4ubuntu2.7 | May 15, 2026 |
| eximon4 · Ubuntu 24.04.5 LTS (noble) | 4.97-4ubuntu4.4 | eximon4 4.97-4ubuntu4.4 | May 15, 2026 |
| eximon4 · Ubuntu 25.10 (questing) | 4.98.2-1ubuntu2.1 | eximon4 4.98.2-1ubuntu2.1 | May 15, 2026 |
| eximon4 · Ubuntu 26.04.1 LTS (resolute) | 4.99.1-1ubuntu1.1 | eximon4 4.99.1-1ubuntu1.1 | Apr 29, 2026 |
Patch Radar data is free to use with attribution. Terms and how to credit it.
Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.