How severe is CVE-2021-44790?

CVE-2021-44790 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-44790 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 97% (100th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-44790?

CVE-2021-44790 primarily affects Apache Http Server. In total, 33 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-44790?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-44790 published?

CVE-2021-44790 was published on 2021-12-20 and last updated on 2026-06-17.

CVE-2021-44790

CVE-2021-44790 is a critical-severity vulnerability in Apache Http Server with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 97% places it in the 100th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-787.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 97% (100th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Apache Http Server
Published: 2021-12-20
Last modified: 2026-06-17

Description

A carefully crafted request body can cause a buffer overflow in the mod_lua multipart parser (r:parsebody() called from Lua scripts). The Apache httpd team is not aware of an exploit for the vulnerabilty though it might be possible to craft one. This issue affects Apache HTTP Server 2.4.51 and earlier.

Frequently asked questions

What is CVE-2021-44790?: A carefully crafted request body can cause a buffer overflow in the mod_lua multipart parser (r:parsebody() called from Lua scripts). The Apache httpd team is not aware of an exploit for the vulnerabilty though it might be possible to craft one. This issue affects Apache HTTP Server 2.4.51 and earlier.
How severe is CVE-2021-44790?: CVE-2021-44790 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-44790 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 97% (100th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-44790?: CVE-2021-44790 primarily affects Apache Http Server. In total, 33 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-44790?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-44790 published?: CVE-2021-44790 was published on 2021-12-20 and last updated on 2026-06-17.

References

Affected products (33)

cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:36:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
cpe:2.3:a:tenable:tenable.sc:*:*:*:*:*:*:*:*
cpe:2.3:a:netapp:cloud_backup:-:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_element_manager:*:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_operations_monitor:4.3:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_operations_monitor:4.4:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_operations_monitor:5.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_session_report_manager:*:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_session_route_manager:*:*:*:*:*:*:*:*
cpe:2.3:a:oracle:http_server:12.2.1.3.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:http_server:12.2.1.4.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:instantis_enterprisetrack:17.1:*:*:*:*:*:*:*
cpe:2.3:a:oracle:instantis_enterprisetrack:17.2:*:*:*:*:*:*:*
cpe:2.3:a:oracle:instantis_enterprisetrack:17.3:*:*:*:*:*:*:*
cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2020-001:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2021-001:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2021-002:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2021-003:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2021-004:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2021-005:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2021-006:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2021-007:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2021-008:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2022-001:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2022-002:*:*:*:*:*:*
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2022-003:*:*:*:*:*:*
cpe:2.3:o:apple:macos:*:*:*:*:*:*:*:*

More vulnerabilities in Apache Http Server

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Browse all CWE-787 (Out-of-bounds Write) vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE:

50.255.62.89 (ipv4-addr)
147.15.15.226 (ipv4-addr)
218.4.91.163 (ipv4-addr)
45.84.120.3 (ipv4-addr)
79.137.34.248 (ipv4-addr)
61.76.112.4 (ipv4-addr)
60.199.224.2 (ipv4-addr)
46.253.45.10 (ipv4-addr)