CVE-2021-22947: Apple macOS
Medium severity, CVSS 5.9. EPSS: 3% chance of exploitation in the next 30 days.
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.
Affected products
- Apple macOS: before 12.3 (fixed in 12.3)
- Debian Debian Linux: version 9.0 only; version 10.0 only; version 11.0 only
- Fedoraproject Fedora: version 33 only; version 35 only
- Haxx Curl: from 7.20.0, before 7.79.0 (fixed in 7.79.0)
- Netapp Cloud Backup: affected versions not specified
- Netapp Clustered Data Ontap: affected versions not specified
- Netapp h300e Firmware: affected versions not specified
- Netapp h300s Firmware: affected versions not specified
- Netapp h410s Firmware: affected versions not specified
- Netapp h500e Firmware: affected versions not specified
- Netapp h500s Firmware: affected versions not specified
- Netapp h700e Firmware: affected versions not specified
- Netapp h700s Firmware: affected versions not specified
- Netapp Solidfire Baseboard Management Controller Firmware: affected versions not specified
- Oracle Commerce Guided Search: version 11.3.2 only
- Oracle Communications Cloud Native Core Binding Support Function: version 1.11.0 only; version 22.1.3 only
- Oracle Communications Cloud Native Core Console: version 22.2.0 only
- Oracle Communications Cloud Native Core Network Function Cloud Native Environment: version 1.10.0 only
- Oracle Communications Cloud Native Core Network Repository Function: version 1.15.0 only; version 1.15.1 only; version 22.1.2 only; version 22.2.0 only
- Oracle Communications Cloud Native Core Network Slice Selection Function: version 1.8.0 only
- Oracle Communications Cloud Native Core Security Edge Protection Proxy: version 22.1.1 only
- Oracle Communications Cloud Native Core Service Communication Proxy: version 1.15.0 only
- Oracle MySQL Server: from 5.7.0, up to and including 5.7.35; from 8.0.0, up to and including 8.0.26
- Oracle PeopleSoft Enterprise PeopleTools: version 8.57 only; version 8.58 only; version 8.59 only
- Siemens Sinec Infrastructure Network Services: before 1.0.1.1 (fixed in 1.0.1.1)
- and 1 more
Published 2021-09-29. Last modified 2026-06-17.