CVE-2021-22945

When sending data to an MQTT server, libcurl <= 7.73.0 and 7.78.0 could in some circumstances erroneously keep a pointer to an already freed memory area and both use that again in a subsequent call to send data and also free it again.

When sending data to an MQTT server, libcurl <= 7.73.0 and 7.78.0 could in some circumstances erroneously keep a pointer to an already freed memory area and both use that again in a subsequent call to send data and also free it again.

When sending data to an MQTT server, libcurl <= 7.73.0 and 7.78.0 could in some circumstances erroneously keep a pointer to an already freed memory area and both use that again in a subsequent call to send data and also free it again.

cURL is a computer software project providing a library (libcurl) and command-line tool (curl) for transferring data using various protocols.

Security Fix(es):

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.(CVE-2021-22947)

A user can tell curl >= 7.20.0 and <= 7.78.0 to require a successful upgrade to TLS when speaking to an IMAP, POP3 or FTP server (--ssl-reqd on the command line orCURLOPT_USE_SSL set to CURLUSESSL_CONTROL or CURLUSESSL_ALL withlibcurl). This requirement could be bypassed if the server would return a properly crafted but perfectly legitimate response.This flaw would then make curl silently continue its operations withoutTLS contrary to the instructions and expectations, exposing possibly sensitive data in clear text over the network.(CVE-2021-22946)

When sending data to an MQTT server, libcurl <= 7.73.0 and 7.78.0 could in some circumstances erroneously keep a pointer to an already freed memory area and both use that again in a subsequent call to send data and also free it again.(CVE-2021-22945)

When sending data to an MQTT server, libcurl <= 7.73.0 and 7.78.0 could in some circumstances erroneously keep a pointer to an already freed memory area and both use that again in a subsequent call to send data and also free it again.

When sending data to an MQTT server, libcurl could in some circumstances erroneously keep a pointer to an already freed memory area and both use that again in a subsequent call to send data and also free it again.

UAF and double-free in MQTT sending. (CVE-2021-22945)

Protocol downgrade required TLS bypassed. (CVE-2021-22946)

STARTTLS protocol injection via MITM. (CVE-2021-22947)

These are all security issues fixed in the curl-7.79.1-1.1 package on the GA media of openSUSE Tumbleweed.

It was discovered that curl incorrect handled memory when sending data to an MQTT server. A remote attacker could use this issue to cause curl to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2021-22945)

Patrick Monnerat discovered that curl incorrectly handled upgrades to TLS. When receiving certain responses from servers, curl would continue without TLS even when the option to require a successful upgrade to TLS was specified. (CVE-2021-22946)

Patrick Monnerat discovered that curl incorrectly handled responses received before STARTTLS. A remote attacker could possibly use this issue to inject responses and intercept communications. (CVE-2021-22947)