Skip to content
Fencer Vulns
medium 5.3

CVE-2021-30641 json

Unexpected URL matching with 'MergeSlashes OFF'

published 2021-06-10 5 y ago modified 2026-09-08 2 mo ago also BIT-apache-2021-30641 , EUVD-2021-17558

cvss
5.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
51.8%
EPSS 51.8% chance of exploitation in 30 days, percentile 98%
public exploits
0
none known

Summary

Apache HTTP Server versions 2.4.39 to 2.4.46 Unexpected matching behavior with 'MergeSlashes OFF'

Patch / fix

  • bitnami apache 2.4.47
  • apache2 Debian 14, Debian 13, Debian 12 2.4.46-6

debian advisories DEBIAN-CVE-2021-30641

  • apache2 Ubuntu 18.04 LTS 2.4.29-1ubuntu4.16
  • apache2 Ubuntu 20.04 LTS 2.4.41-4ubuntu3.3
  • apache2 Ubuntu Pro 14.04 LTS 2.4.7-1ubuntu4.22+esm1
  • apache2 Ubuntu Pro 16.04 LTS 2.4.18-2ubuntu3.17+esm1

ubuntu advisories UBUNTU-CVE-2021-30641

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

  • jbcs-httpd24-apr jboss core services 1 1.6.3-107.jbcs.el7
  • jbcs-httpd24-apr jboss core services 1 1.6.3-107.el8jbcs
  • jbcs-httpd24-curl jboss core services 1 7.78.0-2.jbcs.el7
  • jbcs-httpd24-curl jboss core services 1 7.78.0-2.el8jbcs
  • jbcs-httpd24-httpd jboss core services 1 2.4.37-78.jbcs.el7
  • jbcs-httpd24-httpd jboss core services 1 2.4.37-78.el8jbcs
  • jbcs-httpd24-mod_jk jboss core services 1 1.2.48-20.redhat_1.jbcs.el7
  • jbcs-httpd24-mod_jk jboss core services 1 1.2.48-20.redhat_1.el8jbcs

red hat advisories RHSA-2021:4614RHSA-2021:4257

  • apache2 SLE Module for Server Applications 15 SP3, SLE Module for Server Applications 15 SP2, SLE Module for Package Hub 15 SP3 +2 more 2.4.43-3.22.1
  • apache2 SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +11 more 2.4.23-29.74.1
  • apache2 SLES for SAP 15 SP1, SLES for SAP 15, SLES 15-LTSS +10 more 2.4.33-3.50.1
  • apache2 SLES 11 SP4-LTSS, SLE Point of Sale 11 SP3 2.2.34-70.35.1

suse advisories SUSE-SU-2021:2127-1SUSE-SU-2021:2006-1SUSE-SU-2021:2004-1SUSE-SU-2021:14749-1

  • apache2 openSUSE Leap 15.3 2.4.43-3.22.1
  • apache2 openSUSE Leap 15.2 2.4.43-lp152.2.15.1

opensuse advisories openSUSE-SU-2021:2127-1openSUSE-SU-2021:0908-1

  • mod_md AlmaLinux 8 1:2.0.8-8.module_el8.5.0+2609+b30d9eec
  • mod_md AlmaLinux 8 1:2.0.8-8.module_el8.6.0+2872+fe0ff7aa
  • mod_http2 AlmaLinux 8 1.15.7-3.module_el8.5.0+2609+b30d9eec

almalinux advisories ALSA-2021:4257

  • httpd Rocky Linux 8 2.4.37-41.module+el8.5.0+695+1fa8055e
  • mod_md Rocky Linux 8 1:2.0.8-8.module+el8.5.0+695+1fa8055e
  • mod_md Rocky Linux 8 1:2.0.8-8.module+el8.4.0+553+7a69454b
  • mod_http2 Rocky Linux 8 1.15.7-3.module+el8.4.0+553+7a69454b
  • mod_http2 Rocky Linux 8 1.15.7-3.module+el8.5.0+695+1fa8055e

rocky linux advisories RLSA-2021:4257

  • apache2 Alpine 3.24, Alpine 3.23, Alpine 3.22 +12 more 2.4.48-r0

alpine advisories ALPINE-CVE-2021-30641

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

  • httpd CBL-Mariner 2.0 2.4.46-10

azure linux advisories AZL-6478

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

  • apache Arch Linux 2.4.47-1

arch linux advisories AVG-2053

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-2021-30641 updated cvss 5.9

httpd: Unexpected URL matching with 'MergeSlashes OFF'

  • Red Hat Enterprise Linux 7 httpd, mod_ssl, mod_ldap, httpd-tools, mod_session, httpd-manual, +1 more Red Hat JBoss Enterprise Application Platform 6 httpd22 httpd22 Red Hat JBoss Enterprise Web Server 2 httpd22 httpd22 Red Hat Software Collections httpd24-httpd, httpd24-mod_md, httpd24-mod_ssl, httpd24-mod_ldap, httpd24-httpd-tools, httpd24-mod_session, +2 more
    affected: workaround, no fix planned “This issue can be mitigated by setting the "MergeSlashes" directive to OFF”
  • Red Hat Enterprise Linux AppStream (v. 8) mod_md 2.0.8-8.module+el8.3.0+6814+67d1e611, httpd 2.4.37-41.module+el8.5.0+11772+c8e0c271, mod_http2 1.15.7-3.module+el8.4.0+8625+d397f3da, mod_ssl 2.4.37-41.module+el8.5.0+11772+c8e0c271, mod_ldap 2.4.37-41.module+el8.5.0+11772+c8e0c271, httpd-tools 2.4.37-41.module+el8.5.0+11772+c8e0c271, +4 more
    fixed: vendor fix “This issue can be mitigated by setting the "MergeSlashes" directive to OFF” RHSA-2021:4257
  • Red Hat JBoss Core Services
    fixed: vendor fix “This issue can be mitigated by setting the "MergeSlashes" directive to OFF” RHSA-2021:4613
  • Red Hat JBoss Core Services on RHEL 7 Server jbcs-httpd24-apr 1.6.3-107.jbcs.el7, jbcs-httpd24-curl 7.78.0-2.jbcs.el7, jbcs-httpd24-httpd 2.4.37-78.jbcs.el7, jbcs-httpd24-mod_md 2.0.8-40.jbcs.el7, jbcs-httpd24-libcurl 7.78.0-2.jbcs.el7, jbcs-httpd24-openssl 1.1.1g-8.jbcs.el7, +26 more Red Hat JBoss Core Services on RHEL 8 jbcs-httpd24-apr 1.6.3-107.el8jbcs, jbcs-httpd24-curl 7.78.0-2.el8jbcs, jbcs-httpd24-httpd 2.4.37-78.el8jbcs, jbcs-httpd24-mod_md 2.0.8-40.el8jbcs, jbcs-httpd24-libcurl 7.78.0-2.el8jbcs, jbcs-httpd24-openssl 1.1.1g-8.el8jbcs, +26 more
    fixed: vendor fix “This issue can be mitigated by setting the "MergeSlashes" directive to OFF” RHSA-2021:4614
  • Red Hat Enterprise Linux 6 httpd, mod_ssl, httpd-tools, httpd-manual Red Hat Enterprise Linux 9 httpd, mod_lua, mod_ssl, mod_ldap, httpd-core, httpd-tools, +4 more
    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

51.77% chance of exploitation in the next 30 days, higher than 98% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N
OSV 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
bitnami apache
>=2.4.39, <2.4.47
2.4.47

Affected products

  • Apache Software Foundation Apache HTTP Server

Classification

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.