Unexpected URL matching with 'MergeSlashes OFF'
Priority MEDIUM 56Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · Low · None
- Fix status
- Partial Red Hat: 4 fixed, 4 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.
Summary
Apache HTTP Server versions 2.4.39 to 2.4.46 Unexpected matching behavior with 'MergeSlashes OFF'
Why it matters now
EPSS 0.51765 98th percentileScored 2026-11-07
Fix Partial Red Hat: 3 advisoriesRed Hat: 4 fixed, 4 without a fix
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Apache | Apache HTTP Server | 2.4.46; 2.4.43; 2.4.41; 2.4.39 | — | No fix listed | CNA |
- Apache HTTP Server VendorApache Affected 2.4.46; 2.4.43; 2.4.41; 2.4.39 Fixed in — No fix listed CNA
CPE configurations NVD · 10
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:* | 2.4.39 – 2.4.46 | Vulnerable | Apache |
| cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* | 9.0 | Vulnerable | Debian |
| cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* | 10.0 | Vulnerable | Debian |
| cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* | 34 | Vulnerable | Fedoraproject |
| cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:* | 35 | Vulnerable | Fedoraproject |
| cpe:2.3:a:oracle:enterprise_manager_ops_center:12.4.0.0:*:*:*:*:*:*:* | 12.4.0.0 | Vulnerable | Oracle |
| cpe:2.3:a:oracle:instantis_enterprisetrack:17.1:*:*:*:*:*:*:* | 17.1 | Vulnerable | Oracle |
| cpe:2.3:a:oracle:instantis_enterprisetrack:17.2:*:*:*:*:*:*:* | 17.2 | Vulnerable | Oracle |
| cpe:2.3:a:oracle:instantis_enterprisetrack:17.3:*:*:*:*:*:*:* | 17.3 | Vulnerable | Oracle |
| cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:* | 8.8 | Vulnerable | Oracle |
- cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:* Versions 2.4.39 – 2.4.46 Vulnerable ·Apache
- cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Debian
- cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* Versions 10.0 Vulnerable ·Debian
- cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* Versions 34 Vulnerable ·Fedoraproject
- cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:* Versions 35 Vulnerable ·Fedoraproject
- cpe:2.3:a:oracle:enterprise_manager_ops_center:12.4.0.0:*:*:*:*:*:*:* Versions 12.4.0.0 Vulnerable ·Oracle
- cpe:2.3:a:oracle:instantis_enterprisetrack:17.1:*:*:*:*:*:*:* Versions 17.1 Vulnerable ·Oracle
- cpe:2.3:a:oracle:instantis_enterprisetrack:17.2:*:*:*:*:*:*:* Versions 17.2 Vulnerable ·Oracle
- cpe:2.3:a:oracle:instantis_enterprisetrack:17.3:*:*:*:*:*:*:* Versions 17.3 Vulnerable ·Oracle
- cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:* Versions 8.8 Vulnerable ·Oracle
Remediation
Red Hat 3 advisories
- RHSA-2021:4614 Released 2021-11-10 · Red Hat rating ModerateRed Hat JBoss Core Services Apache HTTP Server 2.4.37 SP10 security update
- Red Hat JBoss Core Services on RHEL 7 Server jbcs-httpd24-apr-1.6.3-107.jbcs.el7, jbcs-httpd24-apr-devel-1.6.3-107.jbcs.el7, jbcs-httpd24-apr-util-1.6.1-84.jbcs.el7 +36
- Red Hat JBoss Core Services on RHEL 8 jbcs-httpd24-apr-1.6.3-107.el8jbcs, jbcs-httpd24-apr-devel-1.6.3-107.el8jbcs, jbcs-httpd24-apr-util-1.6.1-84.el8jbcs +36
- RHSA-2021:4613 Released 2021-11-10 · Red Hat rating ModerateRed Hat JBoss Core Services Apache HTTP Server 2.4.37 SP10 security update
- Red Hat JBoss Core Services
- RHSA-2021:4257 Released 2021-11-09 · Red Hat rating Moderatehttpd:2.4 security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream (v. 8) httpd-2.4.37-41.module+el8.5.0+11772+c8e0c271.aarch64::httpd:2.4, httpd-2.4.37-41.module+el8.5.0+11772+c8e0c271.ppc64le::httpd:2.4, httpd-2.4.37-41.module+el8.5.0+11772+c8e0c271.s390x::httpd:2.4 +38
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Advisory ·
Apache HTTP Server — GLSA-202107-38
7 records Highest priority Priority HIGH 3 HIGH, 4 MEDIUM
Other records, highest priority first
- TI-2021-08375 Apache HTTP Server mod_session response handling heap overflowPriority HIGH 79
- TI-2021-11716 NULL pointer dereference on specially crafted HTTP/2 requestPriority HIGH 71
- TI-2021-08374 mod_session NULL pointer dereferencePriority HIGH 69
- Advisory ·
Apache HTTP Server — DSA-4937
5 records Highest priority Priority HIGH 3 HIGH, 2 MEDIUM
Other records, highest priority first
- TI-2021-08375 Apache HTTP Server mod_session response handling heap overflowPriority HIGH 79
- TI-2021-11716 NULL pointer dereference on specially crafted HTTP/2 requestPriority HIGH 71
- TI-2021-08374 mod_session NULL pointer dereferencePriority HIGH 69
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 7 | Affected | No fix planned: Out of support scope |
| Red Hat JBoss Enterprise Application Platform 6 | Affected | No fix planned: Out of support scope |
| Red Hat JBoss Enterprise Web Server 2 | Affected | No fix planned: Out of support scope |
| Red Hat Software Collections | Affected | No fix planned: Will not fix |
| Red Hat Enterprise Linux AppStream (v. 8) | Fixed | RHSA-2021:4257 |
| Red Hat JBoss Core Services | Fixed | RHSA-2021:4613 |
| Red Hat JBoss Core Services on RHEL 7 Server | Fixed | RHSA-2021:4614 |
| Red Hat JBoss Core Services on RHEL 8 | Fixed | RHSA-2021:4614 |
Not affected: 2 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2021-30641
- 2026-10-03 Alias added: GHSA-jfgv-4796-2jw7
References
Advisory 10
- http://httpd.apache.org/security/vulnerabilities_24.html
- https://lists.apache.org/thread.html/re026d3da9d7824bd93b9f871c0fdda978d960c7e62d8c43cba8d0bf3%40%3Ccvs.httpd.apache.org%3E
- [oss-security] 20210609 CVE-2021-30641: Apache httpd: Unexpected URL matching with 'MergeSlashes OFF'
- [debian-lts-announce] 20210709 [SECURITY] [DLA 2706-1] apache2 security update
- DSA-4937
- GLSA-202107-38
- FEDORA-2021-dce7e7738e
- FEDORA-2021-e3f6dd670d
- https://www.oracle.com/security-alerts/cpuoct2021.html
- https://security.netapp.com/advisory/ntap-20210702-0001/
Other 2
- [httpd-announce] 20210609 CVE-2021-30641: Unexpected URL matching with 'MergeSlashes OFF'
- [httpd-dev] 20210610 Re: svn commit: r1890598 - in /httpd/site/trunk/content/security/json: CVE-2019-17567.json CVE-2020-13938.json CVE-2020-13950.json CVE-2020-35452.json CVE-2021-26690.json CVE-2021-26691.json CVE-2021-30641.json CVE-2021-31618.json
More Apache Http Server vulnerabilities
- TI-2021-18535 Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773) KEVCVSS 3.1CRITICAL 9.8
- TI-2021-18417 Path traversal and file disclosure vulnerability in Apache HTTP Server 2.4.49 KEVCVSS 3.1CRITICAL 9.8
- TI-2024-25716 Apache HTTP Server weakness in mod_rewrite when first segment of substitution matches filesystem path. KEVCVSS 3.1CRITICAL 9.1
- TI-2021-17490 mod_proxy SSRF KEVCVSS 3.1CRITICAL 9.0
- TI-2019-00184 Use after free in Apache HTTP Server KEVCVSS 3.1HIGH 7.8
- TI-2009-03392 The TLS protocol, and the SSL protocol 3.0 and possibly earlier, as used in Microsoft… CVSS 3.1CRITICAL 9.8
Sources
- CVE-2021-30641 · CVE Program
- CVE-2021-30641 · NVD
- FIRST EPSS
- GHSA-jfgv-4796-2jw7 · GitHub Advisory Database · CC BY 4.0
- CVE-2021-30641 · Red Hat security data · CC BY 4.0
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