CVE-2026-28753
Publication date 24 March 2026
Last updated 27 April 2026
Ubuntu priority
Description
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_mail_smtp_module module due to the improper handling of CRLF sequences in DNS responses. This allows an attacker-controlled DNS server to inject arbitrary headers into SMTP upstream requests, leading to potential request manipulation. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| nginx | 26.04 LTS resolute |
Not affected
|
| 25.10 questing |
Fixed 1.28.0-6ubuntu1.2
|
|
| 24.04 LTS noble |
Fixed 1.24.0-2ubuntu7.7
|
|
| 22.04 LTS jammy |
Fixed 1.18.0-6ubuntu14.10
|
|
| 20.04 LTS focal |
Needs evaluation
|
|
| 18.04 LTS bionic |
Needs evaluation
|
|
| 16.04 LTS xenial |
Needs evaluation
|
|
| 14.04 LTS trusty |
Needs evaluation
|
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score |
3.7 · Low
|
| Attack vector | Network |
| Attack complexity | High |
| Privileges required | None |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality | None |
| Integrity impact | Low |
| Availability impact | None |
| Vector | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N |