CVE-2023-27538

An authentication bypass vulnerability exists in libcurl prior to v8.0.0 where it reuses a previously established SSH connection despite the fact that an SSH option was modified, which should have prevented reuse. libcurl maintains a pool of previously used connections to reuse them for subsequent transfers if the configurations match. However, two SSH settings were omitted from the configuration check, allowing them to match easily, potentially leading to the reuse of an inappropriate connection.

An authentication bypass vulnerability exists in libcurl prior to v8.0.0 where it reuses a previously established SSH connection despite the fact that an SSH option was modified, which should have prevented reuse. libcurl maintains a pool of previously used connections to reuse them for subsequent transfers if the configurations match. However, two SSH settings were omitted from the configuration check, allowing them to match easily, potentially leading to the reuse of an inappropriate connection.

An authentication bypass vulnerability exists in libcurl prior to v8.0.0 where it reuses a previously established SSH connection despite the fact that an SSH option was modified, which should have prevented reuse. libcurl maintains a pool of previously used connections to reuse them for subsequent transfers if the configurations match. However, two SSH settings were omitted from the configuration check, allowing them to match easily, potentially leading to the reuse of an inappropriate connection.

An authentication bypass vulnerability exists in libcurl prior to v8.0.0 where it reuses a previously established SSH connection despite the fact that an SSH option was modified, which should have prevented reuse. libcurl maintains a pool of previously used connections to reuse them for subsequent transfers if the configurations match. However, two SSH settings were omitted from the configuration check, allowing them to match easily, potentially leading to the reuse of an inappropriate connection.

An authentication bypass vulnerability exists in libcurl prior to v8.0.0 where it reuses a previously established SSH connection despite the fact that an SSH option was modified, which should have prevented reuse. libcurl maintains a pool of previously used connections to reuse them for subsequent transfers if the configurations match. However, two SSH settings were omitted from the configuration check, allowing them to match easily, potentially leading to the reuse of an inappropriate connection.

An authentication bypass vulnerability exists in libcurl prior to v8.0.0 where it reuses a previously established SSH connection despite the fact that an SSH option was modified, which should have prevented reuse. libcurl maintains a pool of previously used connections to reuse them for subsequent transfers if the configurations match. However, two SSH settings were omitted from the configuration check, allowing them to match easily, potentially leading to the reuse of an inappropriate connection.

An authentication bypass vulnerability exists in libcurl prior to v8.0.0 where it reuses a previously established SSH connection despite the fact that an SSH option was modified, which should have prevented reuse. libcurl maintains a pool of previously used connections to reuse them for subsequent transfers if the configurations match. However, two SSH settings were omitted from the configuration check, allowing them to match easily, potentially leading to the reuse of an inappropriate connection.

An authentication bypass vulnerability exists in libcurl prior to v8.0.0 where it reuses a previously established SSH connection despite the fact that an SSH option was modified, which should have prevented reuse. libcurl maintains a pool of previously used connections to reuse them for subsequent transfers if the configurations match. However, two SSH settings were omitted from the configuration check, allowing them to match easily, potentially leading to the reuse of an inappropriate connection.

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

Security Fix(es):

libcurl keeps previously used connections in a connection pool for subsequent transfers to reuse if one of them matches the setup. However, several FTP settings were left out from the configuration match checks, making them match too easily. The settings in questions are CURLOPT_FTP_ACCOUNT, CURLOPT_FTP_ALTERNATIVE_TO_USER, CURLOPT_FTP_SSL_CCC and CURLOPT_USE_SSL level.(CVE-2023-27535)

libcurl would reuse a previously created connection even when an SSH related option had been changed that should have prohibited reuse. libcurl keeps previously used connections in a connection pool for subsequent transfers to reuse if one of them matches the setup. However, two SSH settings were left out from the configuration match checks, making them match too easily.(CVE-2023-27538)

libcurl would reuse a previously created connection even when the GSS delegation (CURLOPT_GSSAPI_DELEGATION) option had been changed that could have changed the user's permissions in a second transfer. libcurl keeps previously used connections in a connection pool for subsequent transfers to reuse if one of them matches the setup. However, this GSS delegation setting was left out from the configuration match checks, making them match too easily, affecting krb5/kerberos/negotiate/GSSAPI transfers.(CVE-2023-27536)

curl supports communicating using the TELNET protocol and as a part of this it offers users to pass on user name and "telnet options" for the server negotiation. Due to lack of proper input scrubbing and without it being the documented functionality, curl would pass on user name and telnet options to the server as provided. This could allow users to pass in carefully crafted content that pass on content or do option negotiation without the application intending to do so. In particular if an application for example allows users to provide the data or parts of the data.(CVE-2023-27533)

curl supports SFTP transfers. curl's SFTP implementation offers a special feature in the path component of URLs: a tilde (~) character as the first path element in the path to denotes a path relative to the user's home directory. This is supported because of wording in the once proposed to-become RFC draft that was to dictate how SFTP URLs work. Due to a bug, the handling of the tilde in SFTP path did however not only replace it when it is used stand-alone as the first path element but also wrongly when used as a mere prefix in the first element. Using a path like /~2/foo when accessing a server using the user dan (with home directory /home/dan) would then quite suprisingly access the file /home/dan2/foo. This can be taken advantage of to circumvent filtering or worse.(CVE-2023-27534)

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

Security Fix(es):

libcurl keeps previously used connections in a connection pool for subsequent transfers to reuse if one of them matches the setup. However, several FTP settings were left out from the configuration match checks, making them match too easily. The settings in questions are CURLOPT_FTP_ACCOUNT, CURLOPT_FTP_ALTERNATIVE_TO_USER, CURLOPT_FTP_SSL_CCC and CURLOPT_USE_SSL level.(CVE-2023-27535)

libcurl would reuse a previously created connection even when the GSS delegation (CURLOPT_GSSAPI_DELEGATION) option had been changed that could have changed the user's permissions in a second transfer. libcurl keeps previously used connections in a connection pool for subsequent transfers to reuse if one of them matches the setup. However, this GSS delegation setting was left out from the configuration match checks, making them match too easily, affecting krb5/kerberos/negotiate/GSSAPI transfers.(CVE-2023-27536)

curl supports communicating using the TELNET protocol and as a part of this it offers users to pass on user name and "telnet options" for the server negotiation. Due to lack of proper input scrubbing and without it being the documented functionality, curl would pass on user name and telnet options to the server as provided. This could allow users to pass in carefully crafted content that pass on content or do option negotiation without the application intending to do so. In particular if an application for example allows users to provide the data or parts of the data.(CVE-2023-27533)

curl supports SFTP transfers. curl's SFTP implementation offers a special feature in the path component of URLs: a tilde (~) character as the first path element in the path to denotes a path relative to the user's home directory. This is supported because of wording in the once proposed to-become RFC draft that was to dictate how SFTP URLs work. Due to a bug, the handling of the tilde in SFTP path did however not only replace it when it is used stand-alone as the first path element but also wrongly when used as a mere prefix in the first element. Using a path like /~2/foo when accessing a server using the user dan (with home directory /home/dan) would then quite suprisingly access the file /home/dan2/foo. This can be taken advantage of to circumvent filtering or worse.(CVE-2023-27534)

libcurl would reuse a previously created connection even when an SSH related option had been changed that should have prohibited reuse. libcurl keeps previously used connections in a connection pool for subsequent transfers to reuse if one of them matches the setup. However, two SSH settings were left out from the configuration match checks, making them match too easily.(CVE-2023-27538)

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

Security Fix(es):

libcurl keeps previously used connections in a connection pool for subsequent transfers to reuse if one of them matches the setup. However, several FTP settings were left out from the configuration match checks, making them match too easily. The settings in questions are CURLOPT_FTP_ACCOUNT, CURLOPT_FTP_ALTERNATIVE_TO_USER, CURLOPT_FTP_SSL_CCC and CURLOPT_USE_SSL level.(CVE-2023-27535)

libcurl would reuse a previously created connection even when an SSH related option had been changed that should have prohibited reuse. libcurl keeps previously used connections in a connection pool for subsequent transfers to reuse if one of them matches the setup. However, two SSH settings were left out from the configuration match checks, making them match too easily.(CVE-2023-27538)

libcurl would reuse a previously created connection even when the GSS delegation (CURLOPT_GSSAPI_DELEGATION) option had been changed that could have changed the user's permissions in a second transfer. libcurl keeps previously used connections in a connection pool for subsequent transfers to reuse if one of them matches the setup. However, this GSS delegation setting was left out from the configuration match checks, making them match too easily, affecting krb5/kerberos/negotiate/GSSAPI transfers.(CVE-2023-27536)

curl supports communicating using the TELNET protocol and as a part of this it offers users to pass on user name and "telnet options" for the server negotiation. Due to lack of proper input scrubbing and without it being the documented functionality, curl would pass on user name and telnet options to the server as provided. This could allow users to pass in carefully crafted content that pass on content or do option negotiation without the application intending to do so. In particular if an application for example allows users to provide the data or parts of the data.(CVE-2023-27533)

curl supports SFTP transfers. curl's SFTP implementation offers a special feature in the path component of URLs: a tilde (~) character as the first path element in the path to denotes a path relative to the user's home directory. This is supported because of wording in the once proposed to-become RFC draft that was to dictate how SFTP URLs work. Due to a bug, the handling of the tilde in SFTP path did however not only replace it when it is used stand-alone as the first path element but also wrongly when used as a mere prefix in the first element. Using a path like /~2/foo when accessing a server using the user dan (with home directory /home/dan) would then quite suprisingly access the file /home/dan2/foo. This can be taken advantage of to circumvent filtering or worse.(CVE-2023-27534)

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

Security Fix(es):

libcurl keeps previously used connections in a connection pool for subsequent transfers to reuse if one of them matches the setup. However, several FTP settings were left out from the configuration match checks, making them match too easily. The settings in questions are CURLOPT_FTP_ACCOUNT, CURLOPT_FTP_ALTERNATIVE_TO_USER, CURLOPT_FTP_SSL_CCC and CURLOPT_USE_SSL level.(CVE-2023-27535)

libcurl would reuse a previously created connection even when an SSH related option had been changed that should have prohibited reuse. libcurl keeps previously used connections in a connection pool for subsequent transfers to reuse if one of them matches the setup. However, two SSH settings were left out from the configuration match checks, making them match too easily.(CVE-2023-27538)

libcurl would reuse a previously created connection even when the GSS delegation (CURLOPT_GSSAPI_DELEGATION) option had been changed that could have changed the user's permissions in a second transfer. libcurl keeps previously used connections in a connection pool for subsequent transfers to reuse if one of them matches the setup. However, this GSS delegation setting was left out from the configuration match checks, making them match too easily, affecting krb5/kerberos/negotiate/GSSAPI transfers.(CVE-2023-27536)

curl supports communicating using the TELNET protocol and as a part of this it offers users to pass on user name and "telnet options" for the server negotiation. Due to lack of proper input scrubbing and without it being the documented functionality, curl would pass on user name and telnet options to the server as provided. This could allow users to pass in carefully crafted content that pass on content or do option negotiation without the application intending to do so. In particular if an application for example allows users to provide the data or parts of the data.(CVE-2023-27533)

curl supports SFTP transfers. curl's SFTP implementation offers a special feature in the path component of URLs: a tilde (~) character as the first path element in the path to denotes a path relative to the user's home directory. This is supported because of wording in the once proposed to-become RFC draft that was to dictate how SFTP URLs work. Due to a bug, the handling of the tilde in SFTP path did however not only replace it when it is used stand-alone as the first path element but also wrongly when used as a mere prefix in the first element. Using a path like /~2/foo when accessing a server using the user dan (with home directory /home/dan) would then quite suprisingly access the file /home/dan2/foo. This can be taken advantage of to circumvent filtering or worse.(CVE-2023-27534)

An authentication bypass vulnerability exists in libcurl prior to v8.0.0 where it reuses a previously established SSH connection despite the fact that an SSH option was modified, which should have prevented reuse. libcurl maintains a pool of previously used connections to reuse them for subsequent transfers if the configurations match. However, two SSH settings were omitted from the configuration check, allowing them to match easily, potentially leading to the reuse of an inappropriate connection.

The curl packages provide the libcurl library and the curl utility for downloading files from servers using various protocols, including HTTP, FTP, and LDAP.

Security Fix(es):

• curl: GSS delegation too eager connection re-use (CVE-2023-27536)
• curl: TELNET option IAC injection (CVE-2023-27533)
• curl: SFTP path ~ resolving discrepancy (CVE-2023-27534)
• curl: SSH connection too eager reuse still (CVE-2023-27538)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

For detailed information on changes in this release, see the AlmaLinux Release Notes linked from the References section.

• CVE-2023-27538: url: fix the SSH connection reuse check
• CVE-2023-27536: url: only reuse connections with same GSS delegation

libcurl would reuse a previously created connection even when an SSH related option had been changed that should have prohibited reuse.

libcurl keeps previously used connections in a connection pool for subsequent transfers to reuse if one of them matches the setup. However, two SSH settings were left out from the configuration match checks, making them match too easily.

TELNET option IAC injection. (CVE-2023-27533)

SFTP path ~ resolving discrepancy. (CVE-2023-27534)

FTP too eager connection reuse. (CVE-2023-27535)

GSS delegation too eager connection re-use. (CVE-2023-27536)

HSTS double free. (CVE-2023-27537)

SSH connection too eager reuse still. (CVE-2023-27538)

UAF in SSH sha256 fingerprint check. (CVE-2023-28319)

siglongjmp race condition. (CVE-2023-28320)

IDN wildcard match. (CVE-2023-28321)

more POST-after-PUT confusion. (CVE-2023-28322)

HTTP headers eat all memory. (CVE-2023-38039)

These are all security issues fixed in the curl-8.0.1-1.1 package on the GA media of openSUSE Tumbleweed.

This update for curl fixes the following issues:

• CVE-2023-27533: Fixed TELNET option IAC injection (bsc#1209209).
• CVE-2023-27534: Fixed SFTP path ~ resolving discrepancy (bsc#1209210).
• CVE-2023-27535: Fixed FTP too eager connection reuse (bsc#1209211).
• CVE-2023-27536: Fixed GSS delegation too eager connection reuse (bsc#1209212).
• CVE-2023-27538: Fixed SSH connection too eager reuse still (bsc#1209214).

This update for curl fixes the following issues:

• CVE-2023-27533: Fixed TELNET option IAC injection (bsc#1209209).
• CVE-2023-27534: Fixed SFTP path ~ resolving discrepancy (bsc#1209210).
• CVE-2023-27535: Fixed FTP too eager connection reuse (bsc#1209211).
• CVE-2023-27536: Fixed GSS delegation too eager connection reuse (bsc#1209212).
• CVE-2023-27538: Fixed SSH connection too eager reuse still (bsc#1209214).

This update for curl fixes the following issues:

• CVE-2023-27533: Fixed TELNET option IAC injection (bsc#1209209).
• CVE-2023-27534: Fixed SFTP path ~ resolving discrepancy (bsc#1209210).
• CVE-2023-27535: Fixed FTP too eager connection reuse (bsc#1209211).
• CVE-2023-27536: Fixed GSS delegation too eager connection reuse (bsc#1209212).
• CVE-2023-27538: Fixed SSH connection too eager reuse still (bsc#1209214).
• CVE-2023-23916: Fixed HTTP multi-header compression denial of service (bsc#1207992).

This update for curl fixes the following issues:

• CVE-2023-28320: Fixed siglongjmp race condition (bsc#1211231).
• CVE-2023-28321: Fixed IDN wildcard matching (bsc#1211232).
• CVE-2023-28322: Fixed POST-after-PUT confusion (bsc#1211233).
• CVE-2023-27533: Fixed TELNET option IAC injection (bsc#1209209).
• CVE-2023-27534: Fixed SFTP path ~ resolving discrepancy (bsc#1209210).
• CVE-2023-27535: Fixed FTP too eager connection reuse (bsc#1209211).
• CVE-2023-27536: Fixed GSS delegation too eager connection reuse (bsc#1209212).
• CVE-2023-27538: Fixed SSH connection too eager reuse still (bsc#1209214).
• CVE-2022-43552: HTTP Proxy deny use-after-free (bsc#1206309).
• CVE-2023-23916: Fixed HTTP multi-header compression denial of service (bsc#1207992).

This update for curl fixes the following issues:

• CVE-2023-28320: Fixed siglongjmp race condition (bsc#1211231).
• CVE-2023-28321: Fixed IDN wildcard matching (bsc#1211232).
• CVE-2023-28322: Fixed POST-after-PUT confusion (bsc#1211233).
• CVE-2023-27533: Fixed TELNET option IAC injection (bsc#1209209).
• CVE-2023-27534: Fixed SFTP path ~ resolving discrepancy (bsc#1209210).
• CVE-2023-27535: Fixed FTP too eager connection reuse (bsc#1209211).
• CVE-2023-27536: Fixed GSS delegation too eager connection reuse (bsc#1209212).
• CVE-2023-27538: Fixed SSH connection too eager reuse still (bsc#1209214).
• CVE-2022-43552: HTTP Proxy deny use-after-free (bsc#1206309).
• CVE-2023-23916: Fixed HTTP multi-header compression denial of service (bsc#1207992).

Harry Sintonen discovered that curl incorrectly handled certain TELNET connection options. Due to lack of proper input scrubbing, curl could pass on user name and telnet options to the server as provided, contrary to expectations. (CVE-2023-27533)

Harry Sintonen discovered that curl incorrectly handled special tilde characters when used with SFTP paths. A remote attacker could possibly use this issue to circumvent filtering. (CVE-2023-27534)

Harry Sintonen discovered that curl incorrectly reused certain FTP connections. This could lead to the wrong credentials being reused, contrary to expectations. (CVE-2023-27535)

Harry Sintonen discovered that curl incorrectly reused connections when the GSS delegation option had been changed. This could lead to the option being reused, contrary to expectations. (CVE-2023-27536)

Harry Sintonen discovered that curl incorrectly reused certain SSH connections. This could lead to the wrong credentials being reused, contrary to expectations. (CVE-2023-27538)