Vulnerability Database

328,181

Total vulnerabilities in the database

CVE-2021-22947

When curl >= 7.20.0 and <= 7.78.0 connects to an IMAP or POP3 server to retrieve data using STARTTLS to upgrade to TLS security, the server can respond and send back multiple responses at once that curl caches. curl would then upgrade to TLS but not flush the in-queue of cached responses but instead continue using and trustingthe responses it got before the TLS handshake as if they were authenticated.Using this flaw, it allows a Man-In-The-Middle attacker to first inject the fake responses, then pass-through the TLS traffic from the legitimate server and trick curl into sending data back to the user thinking the attacker's injected data comes from the TLS-protected server.

  • Published: Sep 29, 2021
  • Updated: Nov 16, 2025
  • CVE: CVE-2021-22947
  • Severity: Medium
  • Exploit:

CVSS v3:

  • Severity: Medium
  • Score: 5.9
  • AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS v2:

  • Severity: Low
  • Score: 4.3
  • AV:N/AC:M/Au:N/C:N/I:P/A:N
Software From Fixed in
haxx / curl 7.20.0 7.79.0
fedoraproject / fedora 33 33.x
fedoraproject / fedora 35 35.x
debian / debian_linux 9.0 9.0.x
debian / debian_linux 10.0 10.0.x
debian / debian_linux 11.0 11.0.x
oracle / peoplesoft_enterprise_peopletools 8.57 8.57.x
oracle / peoplesoft_enterprise_peopletools 8.58 8.58.x
oracle / peoplesoft_enterprise_peopletools 8.59 8.59.x
oracle / mysql_server 8.0.0 8.0.26.x
oracle / mysql_server 5.7.0 5.7.35.x
oracle / communications_cloud_native_core_network_slice_selection_function 1.8.0 1.8.0.x
oracle / communications_cloud_native_core_network_repository_function 1.15.0 1.15.0.x
oracle / communications_cloud_native_core_network_function_cloud_native_environment 1.10.0 1.10.0.x
oracle / communications_cloud_native_core_service_communication_proxy 1.15.0 1.15.0.x
oracle / communications_cloud_native_core_network_repository_function 1.15.1 1.15.1.x
oracle / communications_cloud_native_core_binding_support_function 1.11.0 1.11.0.x
siemens / sinec_infrastructure_network_services - 1.0.1.1
apple / macos - 12.3
oracle / commerce_guided_search 11.3.2 11.3.2.x
oracle / communications_cloud_native_core_binding_support_function 22.1.3 22.1.3.x
oracle / communications_cloud_native_core_network_repository_function 22.2.0 22.2.0.x
oracle / communications_cloud_native_core_security_edge_protection_proxy 22.1.1 22.1.1.x
oracle / communications_cloud_native_core_console 22.2.0 22.2.0.x
oracle / communications_cloud_native_core_network_repository_function 22.1.2 22.1.2.x
splunk / universal_forwarder 9.1.0 9.1.0.x
splunk / universal_forwarder 9.0.0 9.0.6
splunk / universal_forwarder 8.2.0 8.2.12

Frequently Asked Questions

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.