CVE-2023-51764
Description
A flaw was found in some SMTP server configurations in Postfix. This flaw allows a remote attacker to break out email message data to "smuggle" SMTP commands and send spoofed emails that pass SPF checks.
Out of the box, Postfix targets to accommodate older clients with faulty SMTP implementations due to which restrictions are not enforced in the default configuration. Appropriate mitigation strategies are mentioned in the appropriate section below.
Statement
The impact is considered Moderate likely due to certain conditions required for successful exploitation, such as specific server configurations.
Mitigation
This flaw can be PARTIALLY mitigated via the following options in the main.cf:
smtpd_data_restrictions = reject_unauth_pipelining
smtpd_discard_ehlo_keywords = chunking, silent-discard
Please note this only blocks the misuse of SMTP command pipelining, but does not address message pipelining nor malformed line endings. The only fix for these issues are via package updates.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.3 | 5.3 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | Low | Low | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
