Vulnerability DatabaseWS-2026-0066
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WS-2026-0066
Published:September 07, 2026
Updated:September 10, 2026
Postfix SMTP smuggling via smtpd_proxy_filter: stray CR characters were not eliminated from the proxy filter input stream, so a crafted remote SMTP client could smuggle a line boundary past the before-filter SMTP server when the after-filter SMTP server used the default policy settings smtpd_forbid_bare_newline_exclusions = $mynetworks and smtpd_forbid_bare_newline = normalize. smtpd_proxy_filter is disabled by default. Fixed by smtpd_proxy_fix_line_breaks() in src/smtpd/smtpd_proxy.c.
Affected Packages
https://github.com/vdukhovni/postfix.git (GITHUB):
Affected version(s) >=v3.11.0 <v3.11.7
Fix Suggestion:
Update to version v3.11.7
https://github.com/vdukhovni/postfix.git (GITHUB):
Affected version(s) >=v3.6.14 <v3.6.21
Fix Suggestion:
Update to version v3.6.21
https://github.com/vdukhovni/postfix.git (GITHUB):
Affected version(s) >=v3.10.0 <v3.10.14
Fix Suggestion:
Update to version v3.10.14
https://github.com/vdukhovni/postfix.git (GITHUB):
Affected version(s) >=v3.5.24 <v3.5.28
Fix Suggestion:
Update to version v3.5.28
https://github.com/vdukhovni/postfix.git (GITHUB):
Affected version(s) >=v3.9.0 <v3.9.15
Fix Suggestion:
Update to version v3.9.15
https://github.com/vdukhovni/postfix.git (GITHUB):
Affected version(s) >=v3.7.10 <v3.7.23
Fix Suggestion:
Update to version v3.7.23
https://github.com/vdukhovni/postfix.git (GITHUB):
Affected version(s) >=v3.8.5 <v3.8.21
Fix Suggestion:
Update to version v3.8.21
Related Resources (2)
https://github.com/vdukhovni/postfix/commit/2324a9e97a727bf95690c9fb8fdca0f52301940e
https://www.postfix.org/announcements/postfix-3.11.7.html
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CVSS v4
Base Score:
8.2
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
HIGH
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
5.9
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE
Weakness Type (CWE)
Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
CWE-444