Description
A weakness has been identified in Trusted Domain Project OpenDKIM up to 2.11.0. This affects the function dkim_canon_selecthdrs of the file libopendkim/dkim-canon.c of the component DKIM Signature Header Selection. Executing a manipulation of the argument h can lead to out-of-bounds write. The attack can be executed remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Trusted Domain Project | OpenDKIM | 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 2.10, 2.11.0 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | opendkim | No fix yet | — |
| Debian 13 | opendkim | No fix yet | — |
| Debian 12 | opendkim | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | opendkim | No fix yet | — |
| Ubuntu 26.04 LTS | opendkim | No fix yet | — |
| Ubuntu 24.04 LTS | opendkim | No fix yet | — |
| Ubuntu 22.04 LTS | opendkim | No fix yet | — |
| Ubuntu 20.04 LTS | opendkim | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | opendkim | No fix yet | — |
| Ubuntu 16.04 LTS | opendkim | No fix yet | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | opendkim +3 | 2.11.0-0.42.amzn2023 | ALAS2023-2026-3213 |
Advisories 1
- ALAS2023-2026-3213 Important: opendkim security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Oct 12, 2026
References
- VDB-410837 | Trusted Domain Project OpenDKIM DKIM Signature Header Selection dkim-canon.c dkim_canon_selecthdrs out-of-bounds write vdb-entry technical-description
- VDB-410837 | CTI Indicators (IOB, IOC, IOA) signature permissions-required
- CVE-2026-100888 | CVE Analysis and Report third-party-advisory
- Submit #917015 | The Trusted Domain Project OpenDKIM 2.11.0 Out-of-bounds Write third-party-advisory
- https://weitongli.com/share/opendkim-h-tag-oob-write.html exploit