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Fencer Intel
medium 5.8

CVE-2019-3877 json

A vulnerability was found in mod_auth_mellon before v0.14.2.

published 7y ago modified 4mo ago also EUVD-2019-13488

cvss
5.8
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.1%
EPSS 2.1% chance of exploitation in 30 days, percentile 82%
public exploits
0
none known

Summary

A vulnerability was found in mod_auth_mellon before v0.14.2. An open redirect in the logout URL allows requests with backslashes to pass through by assuming that it is a relative URL, while the browsers silently convert backslash characters into forward slashes treating them as an absolute URL. This mismatch allows an attacker to bypass the redirect URL validation logic in apr_uri_parse function.

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-2019-3877

  • 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-2019-3877

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 8 0.14.0-9.el8
  • mod_auth_mellon-diagnostics RHEL 8 0.14.0-9.el8
  • 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

red hat advisories RHSA-2019:3421RHSA-2019:0766

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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-2019-3877 updated cvss 6.1

mod_auth_mellon: open redirect in logout url when using URLs with backslashes

  • Red Hat Enterprise Linux 6 mod_auth_mellon Red Hat Software Collections httpd24-mod_auth_mellon
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux AppStream (v. 8) mod_auth_mellon 0.14.0-9.el8, mod_auth_mellon-diagnostics 0.14.0-9.el8
    fixed: vendor fix RHSA-2019:3421
  • 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 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

2.12% chance of exploitation in the next 30 days, higher than 82% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.0 5.8 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
NVD 3.0 6.1 CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected products

  • uninett mod_auth_mellon

Classification

Weakness
  • CWE-601 URL Redirection to Untrusted Site

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.