mod_userdir CRLF injection
Possible CRLF injection allowing HTTP response splitting attacks for sites which use mod_userdir. This issue was mitigated by changes made in 2.4.25 and 2.2.32 which prohibit CR or LF injection into the "Location" or other outbound header key or value. Fixed in Apache HTTP Server 2.4.25 (Affected 2.4.1-2.4.23). Fixed in Apache HTTP Server 2.2.32 (Affected 2.2.0-2.2.31).
- Published
- Aug 14, 2018
- Updated
- Jun 16, 2026
- EPSS
- 19.8% · 97th percentile
- CWE
- CWE-93
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Report tools
Action score
30
Monitor
Low priority for now.
- CVSS
- 24 / 40 · 6.1 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 6 / 30 · 19.8%
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpAffected systems
| Vendor | Product | CPE |
|---|---|---|
| apache | http server | cpe:2.3:a:apache:http_server |
Using http server? Add it to your stack and be the first to know about CVEs like this one. (Apache HTTP)
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- apache http server2.2.0
- apache http server2.2.10
- apache http server2.2.11
- apache http server2.2.12
- apache http server2.2.13
- apache http server2.2.14
- apache http server2.2.15
- apache http server2.2.16
- apache http server2.2.17
- apache http server2.2.18
- apache http server2.2.19
- apache http server2.2.2
- apache http server2.2.20
- apache http server2.2.21
- apache http server2.2.22
- apache http server2.2.23
- apache http server2.2.24
- apache http server2.2.25
- apache http server2.2.26
- apache http server2.2.27
Versions reported by the vendor
Affected version ranges reported by the assigning authority (apache). Independent of NVD's CPE analysis and usually ahead of it.
Apache Software Foundation Apache HTTP Server
- Fixed in Apache HTTP Server 2.4.25 (Affected 2.4.1-2.4.23), Fixed in Apache HTTP Server 2.2.32 (Affected 2.2.0-2.2.31)affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | apache2 | before 2.4.25-1 | 2.4.25-1 |
| Red Hat:enterprise_linux:7::client | httpd | before 0:2.4.6-45.el7_3.4 | 0:2.4.6-45.el7_3.4 |
| Red Hat:enterprise_linux:7::client | httpd-debuginfo | before 0:2.4.6-45.el7_3.4 | 0:2.4.6-45.el7_3.4 |
| Red Hat:enterprise_linux:7::client | httpd-devel | before 0:2.4.6-45.el7_3.4 | 0:2.4.6-45.el7_3.4 |
| Red Hat:enterprise_linux:7::client | httpd-manual | before 0:2.4.6-45.el7_3.4 | 0:2.4.6-45.el7_3.4 |
| Red Hat:enterprise_linux:7::client | httpd-tools | before 0:2.4.6-45.el7_3.4 | 0:2.4.6-45.el7_3.4 |
| Red Hat:enterprise_linux:7::client | mod_ldap | before 0:2.4.6-45.el7_3.4 | 0:2.4.6-45.el7_3.4 |
| Red Hat:enterprise_linux:7::client | mod_proxy_html | before 1:2.4.6-45.el7_3.4 | 1:2.4.6-45.el7_3.4 |
| Red Hat:enterprise_linux:7::client | mod_session | before 0:2.4.6-45.el7_3.4 | 0:2.4.6-45.el7_3.4 |
| Red Hat:enterprise_linux:7::client | mod_ssl | before 1:2.4.6-45.el7_3.4 | 1:2.4.6-45.el7_3.4 |
| Red Hat:jboss_core_services:1::el6 | jbcs-httpd24-apache-commons-daemon | before 0:1.1.0-1.redhat_2.1.jbcs.el6 | 0:1.1.0-1.redhat_2.1.jbcs.el6 |
| Red Hat:jboss_core_services:1::el6 | jbcs-httpd24-apache-commons-daemon-jsvc | before 1:1.1.0-1.redhat_2.jbcs.el6 | 1:1.1.0-1.redhat_2.jbcs.el6 |
| Red Hat:jboss_core_services:1::el6 | jbcs-httpd24-apache-commons-daemon-jsvc-debuginfo | before 1:1.1.0-1.redhat_2.jbcs.el6 | 1:1.1.0-1.redhat_2.jbcs.el6 |
| Red Hat:jboss_core_services:1::el6 | jbcs-httpd24-apr | before 0:1.6.3-14.jbcs.el6 | 0:1.6.3-14.jbcs.el6 |
| Red Hat:jboss_core_services:1::el6 | jbcs-httpd24-apr-debuginfo | before 0:1.6.3-14.jbcs.el6 | 0:1.6.3-14.jbcs.el6 |
| Red Hat:jboss_core_services:1::el6 | jbcs-httpd24-apr-devel | before 0:1.6.3-14.jbcs.el6 | 0:1.6.3-14.jbcs.el6 |
| Red Hat:jboss_core_services:1::el6 | jbcs-httpd24-apr-util | before 0:1.6.1-9.jbcs.el6 | 0:1.6.1-9.jbcs.el6 |
| Red Hat:jboss_core_services:1::el6 | jbcs-httpd24-apr-util-debuginfo | before 0:1.6.1-9.jbcs.el6 | 0:1.6.1-9.jbcs.el6 |
| Red Hat:jboss_core_services:1::el6 | jbcs-httpd24-apr-util-devel | before 0:1.6.1-9.jbcs.el6 | 0:1.6.1-9.jbcs.el6 |
| Red Hat:jboss_core_services:1::el6 | jbcs-httpd24-apr-util-ldap | before 0:1.6.1-9.jbcs.el6 | 0:1.6.1-9.jbcs.el6 |
| Red Hat:jboss_core_services:1::el6 | jbcs-httpd24-apr-util-mysql | before 0:1.6.1-9.jbcs.el6 | 0:1.6.1-9.jbcs.el6 |
| Red Hat:jboss_core_services:1::el6 | jbcs-httpd24-apr-util-nss | before 0:1.6.1-9.jbcs.el6 | 0:1.6.1-9.jbcs.el6 |
| Red Hat:jboss_core_services:1::el6 | jbcs-httpd24-apr-util-odbc | before 0:1.6.1-9.jbcs.el6 | 0:1.6.1-9.jbcs.el6 |
| Red Hat:jboss_core_services:1::el6 | jbcs-httpd24-apr-util-openssl | before 0:1.6.1-9.jbcs.el6 | 0:1.6.1-9.jbcs.el6 |
+86
Same product
apache: all recordsOther highest-scoring records for the same primary product.
- CVE-2021-42013Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773)KEV99Now
- CVE-2021-41773Path traversal and file disclosure vulnerability in Apache HTTP Server 2.4.49KEV99Now
- CVE-2024-38475Apache HTTP Server weakness in mod_rewrite when first segment of substitution matches filesystem path.KEV96Now
- CVE-2019-0211In Apache HTTP Server 2.4 releases 2.4.17 to 2.4.38, with MPM event, worker or prefork, code executing in less-privileged child processes orKEV81Now
- CVE-2021-44790Possible buffer overflow when parsing multipart content in mod_lua of Apache HTTP Server 2.4.51 and earlier68This week
- CVE-2010-0425modules/arch/win32/mod_isapi.c in mod_isapi in the Apache HTTP Server 2.0.37 through 2.0.63, 2.2.0 through 2.2.14, and 2.3.x before 2.3.7, w68This week
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:apache2 | 2.4.25-1 · Debian:12 | Package registry (OSV) |
| red hat:httpd | 0:2.4.6-45.el7_3.4 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:httpd-debuginfo | 0:2.4.6-45.el7_3.4 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:httpd-devel | 0:2.4.6-45.el7_3.4 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:httpd-manual | 0:2.4.6-45.el7_3.4 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:httpd-tools | 0:2.4.6-45.el7_3.4 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:jbcs-httpd24-apache-commons-daemon | 0:1.1.0-1.redhat_2.1.jbcs.el7 · Red Hat:jboss_core_services:1::el7 | Package registry (OSV) |
| red hat:jbcs-httpd24-apache-commons-daemon-jsvc | 1:1.1.0-1.redhat_2.jbcs.el7 · Red Hat:jboss_core_services:1::el7 | Package registry (OSV) |
| red hat:jbcs-httpd24-apache-commons-daemon-jsvc-debuginfo | 1:1.1.0-1.redhat_2.jbcs.el7 · Red Hat:jboss_core_services:1::el7 | Package registry (OSV) |
| red hat:mod_ldap | 0:2.4.6-45.el7_3.4 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:mod_proxy_html | 1:2.4.6-45.el7_3.4 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:mod_session | 0:2.4.6-45.el7_3.4 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:mod_ssl | 1:2.4.6-45.el7_3.4 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| suse:apache2 | 2.4.16-20.19.1 · SUSE:Linux Enterprise Server for SAP Applications 12 SP1 | Package registry (OSV) |
Exploit status
Proof of concept available
A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.
Evidence
- Nuclei detection template ×1
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Nuclei detection template | Nuclei template CVE-2016-4975 | — |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- A user must open a link or visit a page.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- low · data can be read
- Integrity
- low · data or configuration can be modified
- Availability
- none
Impact can extend beyond the vulnerable component (scope changes).
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality impact
- Low
- Integrity impact
- Low
- Availability impact
- None
Weakness class (CWE)
CWE-93 · Improper Neutralization of CRLF Sequences ('CRLF Injection')CVSS vector
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- www.securityfocus.com/bid/105093
- httpd.apache.org/security/vulnerabilities_22.html#CVE-2016-4975
- httpd.apache.org/security/vulnerabilities_24.html#CVE-2016-4975
- lists.apache.org/thread.html/56c2e7cc9deb1c12a843d0dc251ea7fd3e7e80293cde02fcd65286ba%40%3Ccvs.httpd.apache.org%3E
- lists.apache.org/thread.html/84a3714f0878781f6ed84473d1a503d2cc382277e100450209231830%40%3Ccvs.httpd.apache.org%3E
- lists.apache.org/thread.html/8d63cb8e9100f28a99429b4328e4e7cebce861d5772ac9863ba2ae6f%40%3Ccvs.httpd.apache.org%3E
- lists.apache.org/thread.html/f7f95ac1cd9895db2714fa3ebaa0b94d0c6df360f742a40951384a53%40%3Ccvs.httpd.apache.org%3E
- lists.apache.org/thread.html/r04e89e873d54116a0635ef2f7061c15acc5ed27ef7500997beb65d6f%40%3Ccvs.httpd.apache.org%3E
- lists.apache.org/thread.html/r57608dc51b79102f3952ae06f54d5277b649c86d6533dcd6a7d201f7%40%3Ccvs.httpd.apache.org%3E
- lists.apache.org/thread.html/r75cbe9ea3e2114e4271bbeca7aff96117b50c1b6eb7c4772b0337c1f%40%3Ccvs.httpd.apache.org%3E
- lists.apache.org/thread.html/r9ea3538f229874c80a10af473856a81fbf5f694cd7f471cc679ba70b%40%3Ccvs.httpd.apache.org%3E
- lists.apache.org/thread.html/r9f93cf6dde308d42a9c807784e8102600d0397f5f834890708bf6920%40%3Ccvs.httpd.apache.org%3E
- lists.apache.org/thread.html/rb14daf9cc4e28d18cdc15d6a6ca74e565672fabf7ad89541071d008b%40%3Ccvs.httpd.apache.org%3E
- lists.apache.org/thread.html/rc998b18880df98bafaade071346690c2bc1444adaa1a1ea464b93f0a%40%3Ccvs.httpd.apache.org%3E
- lists.apache.org/thread.html/rcc44594d4d6579b90deccd4536b5d31f099ef563df39b094be286b9e%40%3Ccvs.httpd.apache.org%3E
- lists.apache.org/thread.html/rd18c3c43602e66f9cdcf09f1de233804975b9572b0456cc582390b6f%40%3Ccvs.httpd.apache.org%3E
- lists.apache.org/thread.html/rd336919f655b7ff309385e34a143e41c503e133da80414485b3abcc9%40%3Ccvs.httpd.apache.org%3E
- lists.apache.org/thread.html/rdca61ae990660bacb682295f2a09d34612b7bb5f457577fe17f4d064%40%3Ccvs.httpd.apache.org%3E
- lists.apache.org/thread.html/re1e3a24664d35bcd0a0e793e0b5fc6ca6c107f99a1b2c545c5d4b467%40%3Ccvs.httpd.apache.org%3E
- lists.apache.org/thread.html/re3d27b6250aa8548b8845d314bb8a350b3df326cacbbfdfe4d455234%40%3Ccvs.httpd.apache.org%3E
Vendor advisories and official records. Exploit/PoC links are deliberately left out.