Summary

Multiple vulnerabilities in cURL libcurl affect AIX. AIX uses cURL libcurl as part of LV/PV encryption integration with HPCS.

Vulnerability Details

**CVEID:**CVE-2022-43552 DESCRIPTION: cURL libcurl is vulnerable to a denial of service, caused by a use-after-free flaw when using an HTTP proxy. By sending a specially-crafted request, a remote attacker could exploit this vulnerability to cause a denial of service condition.
CVSS Base score: 5.9
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/242799 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H)

**CVEID:**CVE-2022-43551 DESCRIPTION: cURL libcurl could allow a remote attacker to bypass security restrictions, caused by a flaw when the host name in the given URL first uses IDN characters that get replaced to ASCII counterparts as part of the IDN conversion. By sending a specially-crafted request, an attacker could exploit this vulnerability to bypass HSTS check.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/242798 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N)

**CVEID:**CVE-2023-27537 DESCRIPTION: cURL libcurl is vulnerable to a denial of service, caused by a double free or use-after-free flaw when sharing HSTS data between separate “handles”. By sending a specially crafted request, a remote attacker could exploit this vulnerability to cause a denial of service condition.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/250532 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

**CVEID:**CVE-2023-27538 DESCRIPTION: cURL libcurl could allow a local attacker to bypass security restrictions, caused by a SSH connection too eager reuse still flaw. By sending a specially crafted request, an attacker could exploit this vulnerability to reuse a previously created connection even when an SSH related option had been changed.
CVSS Base score: 4
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/250533 for the current score.
CVSS Vector: (CVSS:3.0/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N)

**CVEID:**CVE-2023-27534 DESCRIPTION: cURL libcurl could allow a remote attacker to obtain sensitive information, caused by a SFTP path ~ resolving discrepancy flaw. By sending a specially crafted request using a tilde (~) character, an attacker could exploit this vulnerability to obtain sensitive information from other directory, and use this information to launch further attacks against the affected system.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/250529 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N)

**CVEID:**CVE-2023-27535 DESCRIPTION: cURL libcurl could allow a remote attacker to bypass security restrictions, caused by a FTP too eager connection reuse flaw. By sending a specially crafted request, an attacker could exploit this vulnerability to reuse a previously created FTP connection.
CVSS Base score: 5.9
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/250530 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N)

**CVEID:**CVE-2023-27533 DESCRIPTION: cURL libcurl could allow a remote attacker to bypass security restrictions, caused by a TELNET option IAC injection flaw. By sending a specially crafted request, an attacker could exploit this vulnerability to pass on user name and “telnet options” for the server negotiation.
CVSS Base score: 8.2
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/250476 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N)

**CVEID:**CVE-2023-27536 DESCRIPTION: cURL libcurl could allow a remote attacker to bypass security restrictions, caused by a GSS delegation too eager connection re-use flaw. By sending a specially crafted request, an attacker could exploit this vulnerability to reuse a previously created connection even when the GSS delegation.
CVSS Base score: 5.9
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/250531 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N)

**CVEID:**CVE-2022-27782 DESCRIPTION: cURL libcurl could allow a remote attacker to bypass security restrictions, caused by an easy connection reuse flaw for TLS and SSH. By sending a specially-crafted request using the connections in a connection pool, an attacker could exploit this vulnerability to bypass access restrictions.
CVSS Base score: 9.8
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/226252 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)

**CVEID:**CVE-2023-23916 DESCRIPTION: cURL libcurl is vulnerable to a denial of service, caused by a flaw in the decompression chain implementation. By sending a specially-crafted request, a remote attacker could exploit this vulnerability to cause memory errors, and results in a denial of service condition.
CVSS Base score: 7.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/247437 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

**CVEID:**CVE-2022-32206 DESCRIPTION: cURL libcurl is vulnerable to a denial of service, caused by a flaw in the number of acceptable “links” in the “chained” HTTP compression algorithms. By persuading a victim to connect a specially-crafted server, a remote attacker could exploit this vulnerability to insert a virtually unlimited number of compression steps, and results in a denial of service condition.
CVSS Base score: 4.3
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/229740 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L)

Affected Products and Versions

The following fileset levels are vulnerable:

Note: This bulletin does not apply to versions of curl installed from the AIX Toolbox.

To find out whether the affected filesets are installed on your systems, refer to the lslpp command found in AIX user’s guide.

Example: lslpp -L | grep -i oss.lib.libcurl

Remediation/Fixes

A. FIXES

IBM strongly recommends addressing the vulnerability now.

AIX fixes are available. The fixes are cumulative and address previously issued AIX cURL libcurl security bulletins:

https://aix.software.ibm.com/aix/efixes/security/curl_advisory.asc

https://www.ibm.com/support/pages/node/6998763

The AIX fixes can be downloaded via https from:

https://aix.software.ibm.com/aix/efixes/security/curl_fix2.tar

The link above is to a tar file containing this signed advisory, fix packages, and OpenSSL signatures for each package. The fixes below include prerequisite checking. This will enforce the correct mapping between the fixes and AIX Technology Levels.

Please reference the Affected Products and Version section above for help with checking installed fileset levels.

To extract the fixes from the tar file:

tar xvf curl_fix2.tar

cd curl_fix2

Verify you have retrieved the fixes intact:

The checksums below were generated using the “openssl dgst -sha256 [filename]” command as the following:

These sums should match exactly. The OpenSSL signatures in the tar file and on this advisory can also be used to verify the integrity of the fixes. If the sums or signatures cannot be confirmed, contact IBM Support at http://ibm.com/support/ and describe the discrepancy.

openssl dgst -sha256 -verify [pubkey_file] -signature [advisory_file].sig [advisory_file]

openssl dgst -sha256 -verify [pubkey_file] -signature [ifix_file].sig [ifix_file]

Published advisory OpenSSL signature file location:

https://aix.software.ibm.com/aix/efixes/security/curl_advisory2.asc.sig

B. FIX AND INTERIM FIX INSTALLATION

If possible, it is recommended that a mksysb backup of the system be created. Verify it is both bootable and readable before proceeding.

To preview a fix installation:

installp -a -d fix_name -p all # where fix_name is the name of the

fix package being previewed.

To install a fix package:

installp -a -d fix_name -X all # where fix_name is the name of the

fix package being installed.

Interim fixes have had limited functional and regression testing but not the full regression testing that takes place for Service Packs; however, IBM does fully support them.

To preview an interim fix installation:

emgr -e ipkg_name -p # where ipkg_name is the name of the

interim fix package being previewed.

To install an interim fix package:

emgr -e ipkg_name -X # where ipkg_name is the name of the

interim fix package being installed.

Workarounds and Mitigations

None