Malformed requests may cause the server to dereference a NULL pointer. This issue affects Apache HTTP Server 2.4.48 and earlier.
Conclusion & alert: CVE-2021-34798 is rated Moderate Risk (59.5/100): CVSS High severity, with high exploitation likelihood (EPSS 10.29%, 93th percentile). Core evidence: EPSS ranks this CVE among the most likely to be exploited in the near term. Mandatory action: High exploitation likelihood—assess exposure and prioritize remediation.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-03-17 | 13.35% | 10.29% | -3.06% |
| 2 | 2026-03-09 | 11.33% | 13.35% | +2.02% |
| 3 | 2026-03-08 | — | 11.33% | — |
Full EPSS history (73 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 7.5 | 3.1 | HIGH |
|
3.9 | 3.6 | [email protected] |
| 5.0 | 2.0 | MEDIUM |
|
10.0 | 2.9 | [email protected] |
| vendor | priority | summary | link |
|---|---|---|---|
alpine
|
high | CVE-2021-34798: 1 source package rows (apache2); 9 state rows across 9 repos (3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 9, open 0. | https://security.alpinelinux.org/vuln/CVE-2021-34798 |
debian
|
not yet assigned | CVE-2021-34798 not yet assigned priority: Debian including 1 source packages (apache2), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. | https://security-tracker.debian.org/tracker/CVE-2021-34798 |
gentoo
|
high | CVE-2021-34798: 1 GLSA(s) (202208-20), 2 atom(s) (app-admin/apache-tools, www-servers/apache); latest impact high. | https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-34798 |
redhat
|
medium | — | https://access.redhat.com/security/cve/CVE-2021-34798 |
suse
|
high | CVE-2021-34798 severity important: SUSE including 291 source package names (amazon/suse-sles-15-sp1-chost-byos-v20210304-hvm-ssd-x86_64, amazon/suse-sles-15-sp1-chost-byos-v20220127-hvm-ssd-x86_64, …), 501 product×package rows across 60 product lines (HPE Helion OpenStack 8, Image SLES15-SP3-EC2-HVM, … (60 product lines)): Fixed 265, Known Affected 231, Known Not Affected 5. | https://www.suse.com/security/cve/CVE-2021-34798/ |
ubuntu
|
medium | CVE-2021-34798 medium priority: Ubuntu including 1 source packages (apache2), 8 status rows across 8 suites (bionic, focal, hirsute, impish, jammy, trusty, upstream, xenial): released 8. | https://ubuntu.com/security/CVE-2021-34798 |
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| apache | http_server | <= 2.4.48 | cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:* |
| fedoraproject | fedora | 34 | cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* |
| fedoraproject | fedora | 35 | cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:* |
| debian | debian_linux | 9.0 | cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* |
| debian | debian_linux | 10.0 | cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* |
| debian | debian_linux | 11.0 | cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* |
| netapp | cloud_backup | — | cpe:2.3:a:netapp:cloud_backup:-:*:*:*:*:*:*:* |
| netapp | clustered_data_ontap | — | cpe:2.3:a:netapp:clustered_data_ontap:-:*:*:*:*:*:*:* |
| netapp | storagegrid | — | cpe:2.3:a:netapp:storagegrid:-:*:*:*:*:*:*:* |
| tenable | tenable.sc | <= 5.19.1 | cpe:2.3:a:tenable:tenable.sc:*:*:*:*:*:*:*:* |
| oracle | communications_cloud_native_core_network_function_cloud_native_environment | 1.10.0 | cpe:2.3:a:oracle:communications_cloud_native_core_network_function_cloud_native_environment:1.10.0:*:*:*:*:*:*:* |
| oracle | enterprise_manager_base_platform | 13.4.0.0 | cpe:2.3:a:oracle:enterprise_manager_base_platform:13.4.0.0:*:*:*:*:*:*:* |
| oracle | enterprise_manager_base_platform | 13.5.0.0 | cpe:2.3:a:oracle:enterprise_manager_base_platform:13.5.0.0:*:*:*:*:*:*:* |
| oracle | http_server | 12.2.1.3.0 | cpe:2.3:a:oracle:http_server:12.2.1.3.0:*:*:*:*:*:*:* |
| oracle | http_server | 12.2.1.4.0 | cpe:2.3:a:oracle:http_server:12.2.1.4.0:*:*:*:*:*:*:* |
| oracle | instantis_enterprisetrack | 17.1 | cpe:2.3:a:oracle:instantis_enterprisetrack:17.1:*:*:*:*:*:*:* |
| oracle | instantis_enterprisetrack | 17.2 | cpe:2.3:a:oracle:instantis_enterprisetrack:17.2:*:*:*:*:*:*:* |
| oracle | instantis_enterprisetrack | 17.3 | cpe:2.3:a:oracle:instantis_enterprisetrack:17.3:*:*:*:*:*:*:* |
| oracle | peoplesoft_enterprise_peopletools | 8.58 | cpe:2.3:a:oracle:peoplesoft_enterprise_peopletools:8.58:*:*:*:*:*:*:* |
| oracle | zfs_storage_appliance_kit | 8.8 | cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:* |
| broadcom | brocade_fabric_operating_system_firmware | — | cpe:2.3:o:broadcom:brocade_fabric_operating_system_firmware:-:*:*:*:*:*:*:* |
| siemens | ruggedcom_nms | — | cpe:2.3:a:siemens:ruggedcom_nms:*:*:*:*:*:*:*:* |
| siemens | sinec_nms | — | cpe:2.3:a:siemens:sinec_nms:*:*:*:*:*:*:*:* |
| siemens | sinema_remote_connect_server | < 3.1 | cpe:2.3:a:siemens:sinema_remote_connect_server:*:*:*:*:*:*:*:* |
| siemens | sinema_server | 14.0 | cpe:2.3:a:siemens:sinema_server:14.0:-:*:*:*:*:*:* |