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TI-2023-28393 Aliases CVE-2023-51764GHSA-j5jm-hg4x-w8rx

Postfix through 3.8.5 allows SMTP smuggling unless configured with…

Priority LOW 35CWE-345Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
None · Low · None
Fix status
Partial Red Hat: 1 fixed, 3 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-345.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.02635 85th percentileScored 2026-11-07
Public exploit Yes 4 exploit referencesTagged by NVD
Fix Partial Red Hat: 1 advisoryRed Hat: 1 fixed, 3 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
——all versions—No fix listedCNA
  • — Vendor— Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 5

CPEVersionsRoleVendor
cpe:2.3:a:postfix:postfix:*:*:*:*:*:*:*:*before 3.5.23; 3.6.0 to before 3.6.13; 3.7.0 to before 3.7.9; 3.8.0 to before 3.8.4VulnerablePostfix
cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:*38VulnerableFedoraproject
cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:*39VulnerableFedoraproject
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*8.0VulnerableRed Hat
cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*9.0VulnerableRed Hat
  • cpe:2.3:a:postfix:postfix:*:*:*:*:*:*:*:* Versions before 3.5.23; 3.6.0 to before 3.6.13; 3.7.0 to before 3.7.9; 3.8.0 to before 3.8.4 Vulnerable ·Postfix
  • cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:* Versions 38 Vulnerable ·Fedoraproject
  • cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:* Versions 39 Vulnerable ·Fedoraproject
  • cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:* Versions 8.0 Vulnerable ·Red Hat
  • cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Red Hat

Remediation

Red Hat 1 advisory

  • RHSA-2024:9243 Released 2024-11-12 · Red Hat rating Moderate
    postfix security update
    • Red Hat Enterprise Linux AppStream (v. 9) postfix-2:3.5.25-1.el9, postfix-cdb-2:3.5.25-1.el9, postfix-ldap-2:3.5.25-1.el9 +6

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux 7AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux 8AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux AppStream (v. 9)Fixed RHSA-2024:9243

Timeline

  1. 2026-10-02 Threatist record created from CVE-2023-51764
  2. 2026-10-03 Alias added: GHSA-j5jm-hg4x-w8rx
  3. 2026-10-08 CISA SSVC decision points changed

References

Exploit 4

Advisory 7

Other 6

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences