https://hackerone.com/reports/1269242

FEDORA-2021-fc96a3a749

https://www.oracle.com/security-alerts/cpuoct2021.html

The cURL project reports :

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

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

- STARTTLS protocol injection via MITM (CVE-2021-22945)

An update of the curl package has been released.

  - 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)

  - 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 or`CURLOPT_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 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)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The version of curl installed on the remote host is prior to 7.79.0. It is, therefore, affected by multiple vulnerabilities as referenced in the SSA:2021-258-01 advisory.

  - 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)

  - 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)

  - 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 or`CURLOPT_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)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Ubuntu 18.04 LTS / 20.04 LTS / 21.04 host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-5079-1 advisory.

  - 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)

  - 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 or`CURLOPT_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 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)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Severity
153812	FreeBSD : cURL -- Multiple vulnerabilities (c9221ec9-17a2-11ec-b335-d4c9ef517024)	Nessus	FreeBSD Local Security Checks	critical
153505	Photon OS 2.0: Curl PHSA-2021-2.0-0392	Nessus	PhotonOS Local Security Checks	critical
153503	Photon OS 1.0: Curl PHSA-2021-1.0-0434	Nessus	PhotonOS Local Security Checks	critical
153500	Photon OS 3.0: Curl PHSA-2021-3.0-0301	Nessus	PhotonOS Local Security Checks	critical
153494	Photon OS 4.0: Curl PHSA-2021-4.0-0102	Nessus	PhotonOS Local Security Checks	critical
153430	Slackware Linux 14.0 / 14.1 / 14.2 / current curl Multiple Vulnerabilities (SSA:2021-258-01)	Nessus	Slackware Local Security Checks	critical
153407	Ubuntu 18.04 LTS / 20.04 LTS / 21.04 : curl vulnerabilities (USN-5079-1)	Nessus	Ubuntu Local Security Checks	critical

CVE-2021-22945

critical

New! CVE Severity Now Using CVSS v3

Description

References

Details

Risk Information

CVSS v2

CVSS v3

Vulnerable Software

Configuration 1

Configuration 2

Tenable Plugins

critical

critical

critical

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critical