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Fencer Vulns
high 7.5

CVE-2026-27651 json

NGINX ngx_mail_auth_http_module vulnerability

published 2026-03-24 7 mo ago modified 2026-09-08 2 mo ago also BIT-nginx-2026-27651 , BIT-nginx-gateway-2026-27651 , EUVD-2026-14880

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.0%
EPSS 1.0% chance of exploitation in 30 days, percentile 61%
public exploits
0
none known

Summary

When the ngx_mail_auth_http_module module is enabled on NGINX Plus or NGINX Open Source, undisclosed requests can cause worker processes to terminate. This issue may occur when (1) CRAM-MD5 or APOP authentication is enabled, and (2) the authentication server permits retry by returning the Auth-Wait response header. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Patch / fix

  • bitnami nginx 1.28.3, 1.29.7
  • bitnami nginx-gateway 1.28.3, 1.29.7
  • F5 NGINX Open Source 1.28.3, 1.29.7
  • F5 NGINX Plus R32 P5, R35 P2, R36 P3
  • Red Hat Red Hat Enterprise Linux 10 2:1.26.3-2.el10_1.1
  • Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support 2:1.26.3-1.el10_0.8
  • Red Hat Red Hat Enterprise Linux 8 8100020260401080144.489197e6
  • Red Hat Red Hat Enterprise Linux 9 2:1.20.1-24.el9_7.2, 9070020260331134728.9, 9070020260407080353.9
  • Red Hat Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions 1:1.20.1-10.el9_0.3
  • Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions 1:1.20.1-14.el9_2.5
  • Red Hat Red Hat Enterprise Linux 9.4 Extended Update Support 1:1.20.1-16.el9_4.5, 9040020260504195322.9
  • Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support 2:1.20.1-22.el9_6.5, 9060020260504154614.9, 9060020260504194843.9
  • Red Hat Red Hat Hardened Images 1.30.0-1.hum1
  • Red Hat Red Hat Update Infrastructure 5 1776868774, 1776868842
  • nginx Debian 12 1.22.1-9+deb12u5
  • nginx Debian 13 1.26.3-3+deb13u3
  • nginx Debian 14 1.28.3-1

debian advisories DEBIAN-CVE-2026-27651

  • nginx Ubuntu 22.04 LTS 1.18.0-6ubuntu14.10
  • nginx Ubuntu 24.04 LTS 1.24.0-2ubuntu7.7
  • nginx Ubuntu 25.10 1.28.0-6ubuntu1.2
  • nginx Ubuntu Pro 14.04 LTS 1.4.6-1ubuntu3.9+esm6
  • nginx Ubuntu Pro 16.04 LTS 1.10.3-0ubuntu0.16.04.5+esm7
  • nginx Ubuntu Pro 18.04 LTS 1.14.0-0ubuntu1.11+esm2
  • nginx Ubuntu Pro 20.04 LTS 1.18.0-0ubuntu1.7+esm1

ubuntu advisories UBUNTU-CVE-2026-27651

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • nginx hummingbird 1 1.30.0-1.hum1
  • nginx-core hummingbird 1 1.30.0-1.hum1
  • nginx-mod-mail hummingbird 1 1.30.0-1.hum1
  • nginx-filesystem hummingbird 1 1.30.0-1.hum1
  • nginx-mod-stream hummingbird 1 1.30.0-1.hum1
  • nginx-all-modules hummingbird 1 1.30.0-1.hum1
  • nginx-mod-http-perl hummingbird 1 1.30.0-1.hum1
  • nginx-mod-http-geoip hummingbird 1 1.30.0-1.hum1

red hat advisories RHSA-2026:15966RHSA-2026:15943RHSA-2026:15945RHSA-2026:15942RHSA-2026:14836RHSA-2026:13839

  • nginx SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +5 more 1.21.5-150400.3.20.1

suse advisories SUSE-SU-2026:2370-1

  • nginx openSUSE Tumbleweed 1.29.7-1.1

opensuse advisories openSUSE-SU-2026:10423-1

  • nginx AlmaLinux 9 2:1.26.3-2.module_el9.7.0+223+9cd7031b.1
  • nginx-core AlmaLinux 9 2:1.26.3-2.module_el9.7.0+223+9cd7031b.1
  • nginx-mod-mail AlmaLinux 9 2:1.26.3-2.module_el9.7.0+223+9cd7031b.1
  • nginx-filesystem AlmaLinux 9 2:1.26.3-2.module_el9.7.0+223+9cd7031b.1
  • nginx-mod-stream AlmaLinux 9 2:1.26.3-2.module_el9.7.0+223+9cd7031b.1
  • nginx-all-modules AlmaLinux 9 2:1.26.3-2.module_el9.7.0+223+9cd7031b.1
  • nginx-mod-http-perl AlmaLinux 9 2:1.26.3-2.module_el9.7.0+223+9cd7031b.1
  • nginx-mod-http-xslt-filter AlmaLinux 9 2:1.26.3-2.module_el9.7.0+223+9cd7031b.1

almalinux advisories ALSA-2026:7343ALSA-2026:7002ALSA-2026:6906ALSA-2026:6907ALSA-2026:6923

  • nginx Rocky Linux 9 2:1.20.1-24.el9_7.2.rocky.0.1
  • nginx Rocky Linux 9 2:1.26.3-2.module+el9.7.0+40103+2443f6d1
  • nginx Rocky Linux 10 2:1.26.3-2.el10_1.1
  • nginx Rocky Linux 8 1:1.24.0-3.module+el8.10.0+40144+38158758
  • nginx Rocky Linux 9 1:1.24.0-5.module+el9.7.0+40088+99dbd8cd.1.rocky.0.1

rocky linux advisories RLSA-2026:7002RLSA-2026:7343RLSA-2026:6906RLSA-2026:6907RLSA-2026:6923

  • nginx Alpine 3.24, Alpine 3.23, Alpine 3.22 1.28.3-r0

alpine advisories ALPINE-CVE-2026-27651

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • nginx Azure Linux 3.0 1.28.3-1

azure linux advisories AZL-80771

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-27651 updated cvss 7.5

NGINX: NGINX: Denial of Service via undisclosed requests when ngx_mail_auth_http_module is enabled

  • Red Hat CodeReady Linux Builder EUS (v.9.4) nginx-debuginfo 1.20.1-16.el9_4.5, nginx-mod-devel 1.20.1-16.el9_4.5, nginx-debugsource 1.20.1-16.el9_4.5, nginx-core-debuginfo 1.20.1-16.el9_4.5, nginx-mod-mail-debuginfo 1.20.1-16.el9_4.5, nginx-mod-stream-debuginfo 1.20.1-16.el9_4.5, +3 more
    fixed: vendor fix RHSA-2026:13839
  • Red Hat CodeReady Linux Builder EUS (v.9.6) nginx-debuginfo 1.20.1-22.el9_6.5, nginx-mod-devel 1.20.1-22.el9_6.5, nginx-debugsource 1.20.1-22.el9_6.5, nginx-core-debuginfo 1.20.1-22.el9_6.5, nginx-mod-mail-debuginfo 1.20.1-22.el9_6.5, nginx-mod-stream-debuginfo 1.20.1-22.el9_6.5, +3 more
    fixed: vendor fix RHSA-2026:13680
  • Red Hat Enterprise Linux AppStream (v. 8) nginx 1.24.0-3.module+el8.10.0+24155+8a5ade52, nginx-mod-mail 1.24.0-3.module+el8.10.0+24155+8a5ade52, nginx-filesystem 1.24.0-3.module+el8.10.0+24155+8a5ade52, nginx-mod-stream 1.24.0-3.module+el8.10.0+24155+8a5ade52, nginx-all-modules 1.24.0-3.module+el8.10.0+24155+8a5ade52, nginx-mod-http-perl 1.24.0-3.module+el8.10.0+24155+8a5ade52, +2 more
    fixed: vendor fix RHSA-2026:6907
  • Red Hat Enterprise Linux AppStream (v. 9) nginx 1.20.1-24.el9_7.2, nginx-mod-mail 1.20.1-24.el9_7.2, nginx 1.24.0-5.module+el9.7.0+24151+c43a3acf.2, nginx 1.26.3-2.module+el9.7.0+24173+4204b761.1, nginx-core 1.24.0-5.module+el9.7.0+24151+c43a3acf.2, nginx-core 1.26.3-2.module+el9.7.0+24173+4204b761.1, +14 more
    fixed: vendor fix RHSA-2026:6923
  • Red Hat Enterprise Linux AppStream (v. 10) nginx 1.26.3-2.el10_1.1, nginx-mod-mail 1.26.3-2.el10_1.1
    fixed: vendor fix RHSA-2026:6906
  • Red Hat Enterprise Linux AppStream E4S (v.9.0) nginx 1.20.1-10.el9_0.3, nginx-mod-mail 1.20.1-10.el9_0.3, nginx-filesystem 1.20.1-10.el9_0.3, nginx-mod-stream 1.20.1-10.el9_0.3, nginx-all-modules 1.20.1-10.el9_0.3, nginx-mod-http-perl 1.20.1-10.el9_0.3, +2 more
    fixed: vendor fix RHSA-2026:15942
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) nginx 1.20.1-14.el9_2.5, nginx-core 1.20.1-14.el9_2.5, nginx-mod-mail 1.20.1-14.el9_2.5, nginx-filesystem 1.20.1-14.el9_2.5, nginx-mod-stream 1.20.1-14.el9_2.5, nginx-all-modules 1.20.1-14.el9_2.5, +3 more
    fixed: vendor fix RHSA-2026:14836
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) nginx 1.26.3-1.el10_0.8, nginx-core 1.26.3-1.el10_0.8, nginx-mod-mail 1.26.3-1.el10_0.8, nginx-filesystem 1.26.3-1.el10_0.8, nginx-mod-stream 1.26.3-1.el10_0.8, nginx-all-modules 1.26.3-1.el10_0.8, +3 more
    fixed: vendor fix RHSA-2026:13634
show 6 more
  • Red Hat Enterprise Linux AppStream EUS (v.9.4) nginx 1.20.1-16.el9_4.5, nginx-core 1.20.1-16.el9_4.5, nginx-mod-mail 1.20.1-16.el9_4.5, nginx-filesystem 1.20.1-16.el9_4.5, nginx-mod-stream 1.20.1-16.el9_4.5, nginx-all-modules 1.20.1-16.el9_4.5, +12 more
    fixed: vendor fix RHSA-2026:13839
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) nginx 1.20.1-22.el9_6.5, nginx-core 1.20.1-22.el9_6.5, nginx-mod-mail 1.20.1-22.el9_6.5, nginx-filesystem 1.20.1-22.el9_6.5, nginx-mod-stream 1.20.1-22.el9_6.5, nginx-all-modules 1.20.1-22.el9_6.5, +21 more
    fixed: vendor fix RHSA-2026:15945
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) nginx-debuginfo 1.26.3-1.el10_0.8, nginx-mod-devel 1.26.3-1.el10_0.8, nginx-debugsource 1.26.3-1.el10_0.8, nginx-core-debuginfo 1.26.3-1.el10_0.8, nginx-mod-mail-debuginfo 1.26.3-1.el10_0.8, nginx-mod-stream-debuginfo 1.26.3-1.el10_0.8, +3 more
    fixed: vendor fix RHSA-2026:13634
  • Red Hat Hardened Images nginx 1.30.0-1.hum1, nginx-all-modules 1.30.0-1.hum1
    fixed: vendor fix RHSA-2026:8346
  • Red Hat Update Infrastructure 5 rhui5 1776868774, rhui5 1776868842
    fixed: vendor fix RHSA-2026:10065
  • Red Hat Enterprise Linux AppStream (v. 9) nginx 1.20.1-24.el9_7.2, nginx-core 1.20.1-24.el9_7.2, nginx-filesystem 1.20.1-24.el9_7.2, nginx-mod-stream 1.20.1-24.el9_7.2, nginx-all-modules 1.20.1-24.el9_7.2, nginx-mod-http-perl 1.20.1-24.el9_7.2, +2 more Red Hat Enterprise Linux AppStream (v. 10) nginx 1.26.3-2.el10_1.1, nginx-core 1.26.3-2.el10_1.1, nginx-filesystem 1.26.3-2.el10_1.1, nginx-mod-stream 1.26.3-2.el10_1.1, nginx-all-modules 1.26.3-2.el10_1.1, nginx-mod-http-perl 1.26.3-2.el10_1.1, +2 more Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) nginx-debuginfo 1.20.1-24.el9_7.2, nginx-mod-devel 1.20.1-24.el9_7.2, nginx-debugsource 1.20.1-24.el9_7.2, nginx-core-debuginfo 1.20.1-24.el9_7.2, nginx-mod-mail-debuginfo 1.20.1-24.el9_7.2, nginx-mod-stream-debuginfo 1.20.1-24.el9_7.2, +3 more Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) nginx-debuginfo 1.26.3-2.el10_1.1, nginx-mod-devel 1.26.3-2.el10_1.1, nginx-debugsource 1.26.3-2.el10_1.1, nginx-core-debuginfo 1.26.3-2.el10_1.1, nginx-mod-mail-debuginfo 1.26.3-2.el10_1.1, nginx-mod-stream-debuginfo 1.26.3-2.el10_1.1, +3 more Red Hat Update Infrastructure 5 rhui5 1776868744, rhui5 1776868772
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
7 mo ago

Exploit prediction

0.95% chance of exploitation in the next 30 days, higher than 61% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected packages

ecosystem package affected fixed in
bitnami nginx
>=0.5.15, <1.28.3
>=1.29.0, <1.29.7
1.28.3
1.29.7
bitnami nginx-gateway
>=0.5.15, <1.28.3
>=1.29.0, <1.29.7
1.28.3
1.29.7

Affected products

  • F5 NGINX Open Source
  • F5 NGINX Plus
  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions
  • Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
  • Red Hat Red Hat Enterprise Linux 9.4 Extended Update Support
  • Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support
  • Red Hat Red Hat Hardened Images
  • Red Hat Red Hat Update Infrastructure 5

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.