SB2021060321 - cPanel update for EasyApache

Description

This security bulletin contains information about 11 secuirty vulnerabilities.

1) Inadequate encryption strength (CVE-ID: CVE-2021-22897)

The vulnerability allows a remote attacker to force applications use weak cryptographic ciphers.

The vulnerability exists due to a logic error when selecting TLS ciphers during connection via the CURLOPT_SSL_CIPHER_LIST option in libcurl. The selected cipher set was stored in a single "static" variable in the library that is used for multiple concurrent transfers within the specific application, the last one that sets the ciphers will accidentally control the set used by all transfers.

The vulnerability can be triggered when Schannel is used, which is the native TLS library in Microsoft Windows.

2) Use of uninitialized variable (CVE-ID: CVE-2021-22898)

The vulnerability allows a remote attacker to gain access to sensitive information.

The vulnerability exists due to usage of uninitialized variable in code, responsible for processing TELNET requests when parsing NEW_ENV variables. A remote attacker can force the affected application to connect to a telnet server under attackers control and read up to 1800 bytes from the uninitialized memory on the libcurl client system.

Proof of concept:

curl telnet://example.com -tNEW_ENV=a,bbbbbb (256 'b's)

3) Use-after-free (CVE-ID: CVE-2021-22901)

The vulnerability allows a remote attacker to crash the application or compromise the vulnerable system.

The vulnerability exists due to a use-after-free error when processing creation of new TLS sessions or during client certificate negotiation. A remote attacker can force the application to connect to a malicious server, trigger a use-after-free error and crash the application.

Remote code execution is also possible if the application can be forced to initiate multiple transfers with a reused HTTP/1.1 connection or multiplexed HTTP/2 connection in order to inject a crafted memory content into the correct place in memory.

Successful exploitation of the vulnerability may allow an attacker to compromise vulnerable system but requires that libcurl is using OpenSSL.

4) Input validation error (CVE-ID: CVE-2021-30641)

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to incorrect parsing of Apache configuration files. An unexpected section could be matched with 'MergeSlashes OFF' option, leading to a potential security issue.

5) Stack-based buffer overflow (CVE-ID: CVE-2020-35452)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a boundary error when processing Digest nounces in mod_auth_digest. A remote unauthenticated attacker can send a specially crafted HTTP request, trigger stack overflow by one nul byte and crash the server.

6) NULL pointer dereference (CVE-ID: CVE-2020-13950)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dereference error in mod_proxy_http. A remote attacker can pass specially crafted data to the application and perform a denial of service (DoS) attack.

7) Improper Privilege Management (CVE-ID: CVE-2020-13938)

The vulnerability allows a local user to stop the service.

The vulnerability exists due to improper privilege management. A local user can on the Windows system can stop the Apache HTTP server service.

8) Security restrictions bypass (CVE-ID: CVE-2019-17567)

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to unspecified error within the mod_proxy_wstunnel and mod_proxy_http modules. If mod_proxy_wstunnel is configured on an URL that is not necessarily Upgraded by the origin server and is tunneling the whole connection regardless, thus allowing for subsequent requests on the same connection to pass through with no HTTP validation, authentication or authorization possibly configured.

9) NULL pointer dereference (CVE-ID: CVE-2021-31618)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dereference error in mod_http2 in Apache HTTP server. A remote attacker can send specially crafted request to the server and perform a denial of service (DoS) attack.

10) NULL pointer dereference (CVE-ID: CVE-2021-26690)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dereference error in mod_session. A remote attacker can pass specially crafted data to the application and perform a denial of service (DoS) attack.

11) NULL pointer dereference (CVE-ID: CVE-2021-26691)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dereference error in mod_session. A a malicious backend server or SessionHeader can trigger a denial of service (DoS) condition.

Remediation

Install update from vendor's website.

References

• https://news.cpanel.com/easyapache-4-june-2-release/