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Fencer Intel
high 8.1

CVE-2019-3878 json

A vulnerability was found in mod_auth_mellon before v0.14.2.

published 7y ago modified 4mo ago also EUVD-2019-13489

cvss
8.1
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
3.0%
EPSS 3.0% chance of exploitation in 30 days, percentile 87%
public exploits
0
none known

Summary

A vulnerability was found in mod_auth_mellon before v0.14.2. If Apache is configured as a reverse proxy and mod_auth_mellon is configured to only let through authenticated users (with the require valid-user directive), adding special HTTP headers that are normally used to start the special SAML ECP (non-browser based) can be used to bypass authentication.

Patch / fix

  • mod_auth_mellon_project mod_auth_mellon 0.14.2
  • libapache2-mod-auth-mellon Debian 14, Debian 13, Debian 12 0.14.2-1

debian advisories DEBIAN-CVE-2019-3878

  • libapache2-mod-auth-mellon Ubuntu 16.04 LTS 0.12.0-2+deb9u1build0.16.04.1
  • libapache2-mod-auth-mellon Ubuntu 18.04 LTS 0.13.1-1ubuntu0.1
  • libapache2-mod-auth-mellon Ubuntu 20.04 LTS 0.14.2-1ubuntu1

ubuntu advisories UBUNTU-CVE-2019-3878

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

  • mod_auth_mellon RHEL 7 0.14.0-2.el7_6.4
  • mod_auth_mellon-diagnostics RHEL 7 0.14.0-2.el7_6.4
  • httpd24-httpd RHEL 3 SOFTWARE_COLLECTIONS 2.4.34-7.el6.1
  • httpd24-httpd RHEL 3 SOFTWARE_COLLECTIONS 2.4.34-7.el7.1
  • httpd24-mod_auth_mellon RHEL 3 SOFTWARE_COLLECTIONS 0.13.1-2.el7.1
  • httpd24-mod_md RHEL 3 SOFTWARE_COLLECTIONS 2.4.34-7.el7.1
  • httpd24-mod_ssl RHEL 3 SOFTWARE_COLLECTIONS 1:2.4.34-7.el6.1
  • httpd24-mod_ssl RHEL 3 SOFTWARE_COLLECTIONS 1:2.4.34-7.el7.1

red hat advisories RHSA-2019:0766RHSA-2019:0746RHSA-2019:0985

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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-2019-3878 updated cvss 8.1

mod_auth_mellon: authentication bypass in ECP flow

  • Red Hat Enterprise Linux AppStream (v. 8) mod_auth_mellon 0.14.0-3.el8_0.2
    fixed: vendor fix RHSA-2019:0985
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) mod_auth_mellon 0.14.0-2.el7_6.4 Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server Optional (v. 7) mod_auth_mellon-diagnostics 0.14.0-2.el7_6.4 Red Hat Enterprise Linux Server (v. 7) mod_auth_mellon 0.14.0-2.el7_6.4 Red Hat Enterprise Linux Server Optional (v. 7) mod_auth_mellon-diagnostics 0.14.0-2.el7_6.4 Red Hat Enterprise Linux Workstation (v. 7) mod_auth_mellon 0.14.0-2.el7_6.4 Red Hat Enterprise Linux Workstation Optional (v. 7) mod_auth_mellon-diagnostics 0.14.0-2.el7_6.4
    fixed: vendor fix RHSA-2019:0766
  • Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 6) httpd24-httpd 2.4.34-7.el6.1, httpd24-mod_ssl 2.4.34-7.el6.1, httpd24-mod_ldap 2.4.34-7.el6.1, httpd24-httpd-tools 2.4.34-7.el6.1, httpd24-mod_session 2.4.34-7.el6.1, httpd24-httpd-manual 2.4.34-7.el6.1, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7) httpd24-httpd 2.4.34-7.el7.1, httpd24-mod_md 2.4.34-7.el7.1, httpd24-mod_ssl 2.4.34-7.el7.1, httpd24-mod_ldap 2.4.34-7.el7.1, httpd24-httpd-tools 2.4.34-7.el7.1, httpd24-mod_session 2.4.34-7.el7.1, +3 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.4) httpd24-httpd 2.4.34-7.el7.1, httpd24-mod_md 2.4.34-7.el7.1, httpd24-mod_ssl 2.4.34-7.el7.1, httpd24-mod_ldap 2.4.34-7.el7.1, httpd24-httpd-tools 2.4.34-7.el7.1, httpd24-mod_session 2.4.34-7.el7.1, +3 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.5) httpd24-httpd 2.4.34-7.el7.1, httpd24-mod_md 2.4.34-7.el7.1, httpd24-mod_ssl 2.4.34-7.el7.1, httpd24-mod_ldap 2.4.34-7.el7.1, httpd24-httpd-tools 2.4.34-7.el7.1, httpd24-mod_session 2.4.34-7.el7.1, +3 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.6) httpd24-httpd 2.4.34-7.el7.1, httpd24-mod_md 2.4.34-7.el7.1, httpd24-mod_ssl 2.4.34-7.el7.1, httpd24-mod_ldap 2.4.34-7.el7.1, httpd24-httpd-tools 2.4.34-7.el7.1, httpd24-mod_session 2.4.34-7.el7.1, +3 more Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 6) httpd24-httpd 2.4.34-7.el6.1, httpd24-mod_ssl 2.4.34-7.el6.1, httpd24-mod_ldap 2.4.34-7.el6.1, httpd24-httpd-tools 2.4.34-7.el6.1, httpd24-mod_session 2.4.34-7.el6.1, httpd24-httpd-manual 2.4.34-7.el6.1, +1 more
    +1 more products
    Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7) httpd24-httpd 2.4.34-7.el7.1, httpd24-mod_md 2.4.34-7.el7.1, httpd24-mod_ssl 2.4.34-7.el7.1, httpd24-mod_ldap 2.4.34-7.el7.1, httpd24-httpd-tools 2.4.34-7.el7.1, httpd24-mod_session 2.4.34-7.el7.1, +3 more
    fixed: vendor fix RHSA-2019:0746
  • Red Hat Enterprise Linux 6 mod_auth_mellon
    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

Exploit prediction

2.97% chance of exploitation in the next 30 days, higher than 87% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/Uninett/mod_auth_mellon/pull/196 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.0 8.1 CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
NVD 3.0 8.1 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P

Affected products

  • uninett mod_auth_mellon

Classification

Weakness
  • CWE-305 Authentication Bypass by Primary Weakness
  • CWE-287 Improper Authentication

References

Sources

Fencer Intel 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.