mod_proxy_http NULL pointer dereference
Apache HTTP Server versions 2.4.41 to 2.4.46 mod_proxy_http can be made to crash (NULL pointer dereference) with specially crafted requests using both Content-Length and Transfer-Encoding headers, leading to a Denial of Service
- Published
- Jun 10, 2021
- Updated
- Jun 16, 2026
- EPSS
- 49.4% · 99th percentile
- CWE
- CWE-476
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Report tools
Action score
45
Plan
Add it to your regular patch cycle.
- CVSS
- 30 / 40 · 7.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 15 / 30 · 49.4%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| apache | http server | cpe:2.3:a:apache:http_server |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
| fedoraproject | fedora | cpe:2.3:o:fedoraproject:fedora |
| oracle | enterprise manager ops center | cpe:2.3:a:oracle:enterprise_manager_ops_center |
| oracle | instantis enterprisetrack | cpe:2.3:a:oracle:instantis_enterprisetrack |
| oracle | zfs storage appliance kit | cpe:2.3:a:oracle:zfs_storage_appliance_kit |
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 server2.4.41 and later · up to 2.4.46 inclusive
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
- 2.4.46, 2.4.43, 2.4.41affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Alpine:v3.10 | apache2 | before 2.4.48-r0 | 2.4.48-r0 |
| Debian:12 | apache2 | before 2.4.46-6 | 2.4.46-6 |
| openSUSE:Leap 15.2 | apache2 | before 2.4.43-lp152.2.15.1 | 2.4.43-lp152.2.15.1 |
| openSUSE:Leap 15.3 | apache2 | before 2.4.43-3.22.1 | 2.4.43-3.22.1 |
| Red Hat:enterprise_linux:8::appstream | httpd | before 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 | 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 |
| Red Hat:enterprise_linux:8::appstream | httpd-debuginfo | before 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 | 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 |
| Red Hat:enterprise_linux:8::appstream | httpd-debugsource | before 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 | 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 |
| Red Hat:enterprise_linux:8::appstream | httpd-devel | before 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 | 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 |
| Red Hat:enterprise_linux:8::appstream | httpd-filesystem | before 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 | 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 |
| Red Hat:enterprise_linux:8::appstream | httpd-manual | before 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 | 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 |
| Red Hat:enterprise_linux:8::appstream | httpd-tools | before 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 | 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 |
| Red Hat:enterprise_linux:8::appstream | httpd-tools-debuginfo | before 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 | 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 |
| Red Hat:enterprise_linux:8::appstream | mod_http2 | before 0:1.15.7-5.module+el8.6.0+13996+01710940 | 0:1.15.7-5.module+el8.6.0+13996+01710940 |
| Red Hat:enterprise_linux:8::appstream | mod_http2-debuginfo | before 0:1.15.7-5.module+el8.6.0+13996+01710940 | 0:1.15.7-5.module+el8.6.0+13996+01710940 |
| Red Hat:enterprise_linux:8::appstream | mod_http2-debugsource | before 0:1.15.7-5.module+el8.6.0+13996+01710940 | 0:1.15.7-5.module+el8.6.0+13996+01710940 |
| Red Hat:enterprise_linux:8::appstream | mod_ldap | before 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 | 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 |
| Red Hat:enterprise_linux:8::appstream | mod_ldap-debuginfo | before 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 | 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 |
| Red Hat:enterprise_linux:8::appstream | mod_md | before 1:2.0.8-8.module+el8.3.0+6814+67d1e611 | 1:2.0.8-8.module+el8.3.0+6814+67d1e611 |
| Red Hat:enterprise_linux:8::appstream | mod_md-debuginfo | before 1:2.0.8-8.module+el8.3.0+6814+67d1e611 | 1:2.0.8-8.module+el8.3.0+6814+67d1e611 |
| Red Hat:enterprise_linux:8::appstream | mod_md-debugsource | before 1:2.0.8-8.module+el8.3.0+6814+67d1e611 | 1:2.0.8-8.module+el8.3.0+6814+67d1e611 |
| Red Hat:enterprise_linux:8::appstream | mod_proxy_html | before 1:2.4.37-47.module+el8.6.0+15654+427eba2e.2 | 1:2.4.37-47.module+el8.6.0+15654+427eba2e.2 |
| Red Hat:enterprise_linux:8::appstream | mod_proxy_html-debuginfo | before 1:2.4.37-47.module+el8.6.0+15654+427eba2e.2 | 1:2.4.37-47.module+el8.6.0+15654+427eba2e.2 |
| Red Hat:enterprise_linux:8::appstream | mod_session | before 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 | 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 |
| Red Hat:enterprise_linux:8::appstream | mod_session-debuginfo | before 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 | 0:2.4.37-47.module+el8.6.0+15654+427eba2e.2 |
+96
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 |
|---|---|---|
| Alpine:apache2 | 2.4.48-r0 · Alpine:v3.10 | Package registry (OSV) |
| Debian:apache2 | 2.4.46-6 · Debian:12 | Package registry (OSV) |
| openSUSE:apache2 | 2.4.43-lp152.2.15.1 · openSUSE:Leap 15.2 | Package registry (OSV) |
| Red Hat:jbcs-httpd24-apr | 0:1.6.3-107.jbcs.el7 · Red Hat:jboss_core_services:1::el7 | Package registry (OSV) |
| Red Hat:jbcs-httpd24-apr-debuginfo | 0:1.6.3-107.jbcs.el7 · Red Hat:jboss_core_services:1::el7 | Package registry (OSV) |
| Red Hat:jbcs-httpd24-apr-devel | 0:1.6.3-107.jbcs.el7 · Red Hat:jboss_core_services:1::el7 | Package registry (OSV) |
| Red Hat:jbcs-httpd24-apr-util | 0:1.6.1-84.jbcs.el7 · Red Hat:jboss_core_services:1::el7 | Package registry (OSV) |
| Red Hat:jbcs-httpd24-apr-util-debuginfo | 0:1.6.1-84.jbcs.el7 · Red Hat:jboss_core_services:1::el7 | Package registry (OSV) |
| Red Hat:jbcs-httpd24-apr-util-devel | 0:1.6.1-84.jbcs.el7 · Red Hat:jboss_core_services:1::el7 | Package registry (OSV) |
| Red Hat:jbcs-httpd24-apr-util-ldap | 0:1.6.1-84.jbcs.el7 · Red Hat:jboss_core_services:1::el7 | Package registry (OSV) |
| Red Hat:jbcs-httpd24-apr-util-mysql | 0:1.6.1-84.jbcs.el7 · Red Hat:jboss_core_services:1::el7 | Package registry (OSV) |
| Red Hat:jbcs-httpd24-apr-util-nss | 0:1.6.1-84.jbcs.el7 · Red Hat:jboss_core_services:1::el7 | Package registry (OSV) |
| Red Hat:jbcs-httpd24-apr-util-odbc | 0:1.6.1-84.jbcs.el7 · Red Hat:jboss_core_services:1::el7 | Package registry (OSV) |
| Red Hat:jbcs-httpd24-apr-util-openssl | 0:1.6.1-84.jbcs.el7 · Red Hat:jboss_core_services:1::el7 | Package registry (OSV) |
| Red Hat:jbcs-httpd24-apr-util-pgsql | 0:1.6.1-84.jbcs.el7 · Red Hat:jboss_core_services:1::el7 | Package registry (OSV) |
| Rocky Linux:httpd | 0:2.4.37-47.module+el8.6.0+823+f143cee1.1 · Rocky Linux:8 | Package registry (OSV) |
| Rocky Linux:mod_http2 | 0:1.15.7-5.module+el8.6.0+823+f143cee1 · Rocky Linux:8 | Package registry (OSV) |
| Rocky Linux:mod_md | 1:2.0.8-8.module+el8.5.0+695+1fa8055e · Rocky Linux:8 | Package registry (OSV) |
| SUSE:apache2 | 2.4.43-3.22.1 · SUSE:Linux Enterprise Module for Basesystem 15 SP2 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
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.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-476 · NULL Pointer DereferenceCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; 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 helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- httpd.apache.org/security/vulnerabilities_24.html
- www.openwall.com/lists/oss-security/2021/06/10/4
- lists.apache.org/thread.html/r7f2b70b621651548f4b6f027552f1dd91705d7111bb5d15cda0a68dd%40%3Cdev.httpd.apache.org%3E
- lists.apache.org/thread.html/rbe197409ae4a58b629fb792d1aed541ccbbf865121a80e1c5938d223%40%3Cannounce.httpd.apache.org%3E
- lists.apache.org/thread.html/re026d3da9d7824bd93b9f871c0fdda978d960c7e62d8c43cba8d0bf3%40%3Ccvs.httpd.apache.org%3E
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SPBR6WUYBJNACHKE65SPL7TJOHX7RHWD/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZNCYSR3BXT36FFF4XTCPL3HDQK4VP45R/
- security.gentoo.org/glsa/202107-38
- security.netapp.com/advisory/ntap-20210702-0001/
- www.oracle.com/security-alerts/cpuoct2021.html
Vendor advisories and official records. Exploit/PoC links are deliberately left out.