Postfix up to 3.5.23/3.6.13/3.7.9/3.8.4 Email Message protection mechanism

Summaryinfo

A vulnerability described as problematic has been identified in Postfix up to 3.5.23/3.6.13/3.7.9/3.8.4. Impacted is an unknown function of the component Email Message Handler. The manipulation results in protection mechanism. This vulnerability is identified as CVE-2023-51764. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in Postfix up to 3.5.23/3.6.13/3.7.9/3.8.4. It has been classified as problematic. Affected is an unknown code block of the component Email Message Handler. The manipulation with an unknown input leads to a protection mechanism vulnerability. CWE is classifying the issue as CWE-693. The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product. This is going to have an impact on integrity. CVE summarizes:

Postfix through 3.8.5 allows SMTP smuggling unless configured with smtpd_data_restrictions=reject_unauth_pipelining and smtpd_discard_ehlo_keywords=chunking (or certain other options that exist in recent versions). Remote attackers can use a published exploitation technique to inject e-mail messages with a spoofed MAIL FROM address, allowing bypass of an SPF protection mechanism. This occurs because Postfix supports <LF>.<CR><LF> but some other popular e-mail servers do not. To prevent attack variants (by always disallowing <LF> without <CR>), a different solution is required, such as the smtpd_forbid_bare_newline=yes option with a Postfix minimum version of 3.5.23, 3.6.13, 3.7.9, 3.8.4, or 3.9.

The weakness was released 12/24/2023. The advisory is available at sec-consult.com. This vulnerability is traded as CVE-2023-51764 since 12/24/2023. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $5k-$25k at the moment (estimation calculated on 11/06/2025).

The vulnerability scanner Nessus provides a plugin with the ID 210837 (RHEL 9 : postfix (RHSA-2024:9243)), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at Tenable (210837). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Name

• Postfix

Version

• 3.5.0
• 3.5.1
• 3.5.2
• 3.5.3
• 3.5.4
• 3.5.5
• 3.5.6
• 3.5.7
• 3.5.8
• 3.5.9
• 3.5.10
• 3.5.11
• 3.5.12
• 3.5.13
• 3.5.14
• 3.5.15
• 3.5.16
• 3.5.17
• 3.5.18
• 3.5.19
• 3.5.20
• 3.5.21
• 3.5.22
• 3.5.23
• 3.6.0
• 3.6.1
• 3.6.2
• 3.6.3
• 3.6.4
• 3.6.5
• 3.6.6
• 3.6.7
• 3.6.8
• 3.6.9
• 3.6.10
• 3.6.11
• 3.6.12
• 3.6.13
• 3.7.0
• 3.7.1
• 3.7.2
• 3.7.3
• 3.7.4
• 3.7.5
• 3.7.6
• 3.7.7
• 3.7.8
• 3.7.9
• 3.8.0
• 3.8.1
• 3.8.2
• 3.8.3
• 3.8.4

CPE 2.3info

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CPE 2.2info

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Entryinfo

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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