CVE-2021-22999

On versions 15.0.x before 15.1.0 and 14.1.x before 14.1.4, the BIG-IP system provides an option to connect HTTP/2 clients to HTTP/1.x servers. When a client is slow to accept responses and it closes a connection prematurely, the BIG-IP system may indefinitely retain some streams unclosed. Note: Software versions which have reached End of Software Development (EoSD) are not evaluated.

Published: 2021-03-31 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-22999 is rated Moderate Risk (53.8/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.65%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-22999

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 2025-03-30 0.77% 0.65% -0.12%
2 2025-03-29 0.65% 0.77% +0.12%
3 2025-03-17 — 0.65% —

Full EPSS history (8 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-22999

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-22999

Affected software / configurations for CVE-2021-22999

Vendor Product Version Raw CPE
f5 big-ip_access_policy_manager >= 14.1.0, < 14.1.4 cpe:2.3:a:f5:big-ip_access_policy_manager:*:*:*:*:*:*:*:*
f5 big-ip_access_policy_manager >= 15.0.0, < 15.1.0 cpe:2.3:a:f5:big-ip_access_policy_manager:*:*:*:*:*:*:*:*
f5 big-ip_advanced_firewall_manager >= 14.1.0, < 14.1.4 cpe:2.3:a:f5:big-ip_advanced_firewall_manager:*:*:*:*:*:*:*:*
f5 big-ip_advanced_firewall_manager >= 15.0.0, < 15.1.0 cpe:2.3:a:f5:big-ip_advanced_firewall_manager:*:*:*:*:*:*:*:*
f5 big-ip_advanced_web_application_firewall >= 14.1.0, < 14.1.4 cpe:2.3:a:f5:big-ip_advanced_web_application_firewall:*:*:*:*:*:*:*:*
f5 big-ip_advanced_web_application_firewall >= 15.0.0, < 15.1.0 cpe:2.3:a:f5:big-ip_advanced_web_application_firewall:*:*:*:*:*:*:*:*
f5 big-ip_analytics >= 14.1.0, < 14.1.4 cpe:2.3:a:f5:big-ip_analytics:*:*:*:*:*:*:*:*
f5 big-ip_analytics >= 15.0.0, < 15.1.0 cpe:2.3:a:f5:big-ip_analytics:*:*:*:*:*:*:*:*
f5 big-ip_application_acceleration_manager >= 14.1.0, < 14.1.4 cpe:2.3:a:f5:big-ip_application_acceleration_manager:*:*:*:*:*:*:*:*
f5 big-ip_application_acceleration_manager >= 15.0.0, < 15.1.0 cpe:2.3:a:f5:big-ip_application_acceleration_manager:*:*:*:*:*:*:*:*
f5 big-ip_application_security_manager >= 14.1.0, < 14.1.4 cpe:2.3:a:f5:big-ip_application_security_manager:*:*:*:*:*:*:*:*
f5 big-ip_application_security_manager >= 15.0.0, < 15.1.0 cpe:2.3:a:f5:big-ip_application_security_manager:*:*:*:*:*:*:*:*
f5 big-ip_ddos_hybrid_defender >= 14.1.0, < 14.1.4 cpe:2.3:a:f5:big-ip_ddos_hybrid_defender:*:*:*:*:*:*:*:*
f5 big-ip_ddos_hybrid_defender >= 15.0.0, < 15.1.0 cpe:2.3:a:f5:big-ip_ddos_hybrid_defender:*:*:*:*:*:*:*:*
f5 big-ip_domain_name_system >= 14.1.0, < 14.1.4 cpe:2.3:a:f5:big-ip_domain_name_system:*:*:*:*:*:*:*:*
f5 big-ip_domain_name_system >= 15.0.0, < 15.1.0 cpe:2.3:a:f5:big-ip_domain_name_system:*:*:*:*:*:*:*:*
f5 big-ip_fraud_protection_service >= 14.1.0, < 14.1.4 cpe:2.3:a:f5:big-ip_fraud_protection_service:*:*:*:*:*:*:*:*
f5 big-ip_fraud_protection_service >= 15.0.0, < 15.1.0 cpe:2.3:a:f5:big-ip_fraud_protection_service:*:*:*:*:*:*:*:*
f5 big-ip_global_traffic_manager >= 14.1.0, < 14.1.4 cpe:2.3:a:f5:big-ip_global_traffic_manager:*:*:*:*:*:*:*:*
f5 big-ip_global_traffic_manager >= 15.0.0, < 15.1.0 cpe:2.3:a:f5:big-ip_global_traffic_manager:*:*:*:*:*:*:*:*
f5 big-ip_link_controller >= 14.1.0, < 14.1.4 cpe:2.3:a:f5:big-ip_link_controller:*:*:*:*:*:*:*:*
f5 big-ip_link_controller >= 15.0.0, < 15.1.0 cpe:2.3:a:f5:big-ip_link_controller:*:*:*:*:*:*:*:*
f5 big-ip_local_traffic_manager >= 14.1.0, < 14.1.4 cpe:2.3:a:f5:big-ip_local_traffic_manager:*:*:*:*:*:*:*:*
f5 big-ip_local_traffic_manager >= 15.0.0, < 15.1.0 cpe:2.3:a:f5:big-ip_local_traffic_manager:*:*:*:*:*:*:*:*
f5 big-ip_policy_enforcement_manager >= 14.1.0, < 14.1.4 cpe:2.3:a:f5:big-ip_policy_enforcement_manager:*:*:*:*:*:*:*:*
f5 big-ip_policy_enforcement_manager >= 15.0.0, < 15.1.0 cpe:2.3:a:f5:big-ip_policy_enforcement_manager:*:*:*:*:*:*:*:*
f5 ssl_orchestrator >= 14.1.0, < 14.1.4 cpe:2.3:a:f5:ssl_orchestrator:*:*:*:*:*:*:*:*
f5 ssl_orchestrator >= 15.0.0, < 15.1.0 cpe:2.3:a:f5:ssl_orchestrator:*:*:*:*:*:*:*:*

References for CVE-2021-22999

cvelogic Threat Intelligence