Gentoo update for cURL
| Risk | High |
| Patch available | YES |
| Number of vulnerabilities | 4 |
| CVE-ID | CVE-2021-22876 CVE-2021-22890 CVE-2021-22898 CVE-2021-22901 |
| CWE-ID | CWE-200 CWE-300 CWE-457 CWE-416 |
| Exploitation vector | Network |
| Public exploit | N/A |
| Vulnerable software |
Gentoo Linux Operating systems & Components / Operating system |
| Vendor | Gentoo |
Security Bulletin
This security bulletin contains information about 4 vulnerabilities.
1) Information disclosure
EUVDB-ID: #VU51821
Risk: Medium
CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C]
CVE-ID: CVE-2021-22876
CWE-ID:
CWE-200 - Information exposure
Exploit availability: No
DescriptionThe vulnerability allows a remote attacker to gain access to potentially sensitive information.
The vulnerability exists due to libcurl does not strip off user credentials from the URL when automatically populating the Referer:
HTTP request header field in outgoing HTTP requests and therefore
risks leaking sensitive data to the server that is the target of the
second HTTP request.
Update the affected packages.
net-misc/curl to version: 7.77.0
Gentoo Linux: All versions
CPE2.3 External linkshttp://security.gentoo.org/
http://security.gentoo.org/glsa/202105-36
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
2) Man-in-the-Middle (MitM) attack
EUVDB-ID: #VU51822
Risk: Medium
CVSSv3.1: 5.3 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N/E:U/RL:O/RC:C]
CVE-ID: CVE-2021-22890
CWE-ID:
CWE-300 - Channel Accessible by Non-Endpoint ('Man-in-the-Middle')
Exploit availability: No
DescriptionThe vulnerability allows a remote attacker to perform MitM attack.
The vulnerability exists due to an error when handling TLS 1.3 session tickets. When using a HTTPS proxy and TLS 1.3, libcurl can confuse session tickets arriving from the HTTPS proxy but work as if they arrived from the remote server and then wrongly "short-cut" the host handshake. The reason for this confusion is the modified sequence from TLS 1.2 when the session ids would provided only during the TLS handshake, while in TLS 1.3 it happens post hand-shake and the code was not updated to take that changed behavior into account.
When confusing the tickets, a HTTPS proxy can trick libcurl to use the wrong session ticket resume for the host and thereby circumvent the server TLS certificate check and make a MITM attack to be possible to perform unnoticed.
This flaw can allow a malicious HTTPS proxy to MITM the traffic. Such a malicious HTTPS proxy needs to provide a certificate that curl will accept for the MITMed server for an attack to work - unless curl has been told to ignore the server certificate check.
MitigationUpdate the affected packages.
net-misc/curl to version: 7.77.0
Gentoo Linux: All versions
CPE2.3 External linkshttp://security.gentoo.org/
http://security.gentoo.org/glsa/202105-36
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
3) Use of uninitialized variable
EUVDB-ID: #VU53587
Risk: Medium
CVSSv3.1: 4.1 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N/E:U/RL:O/RC:C]
CVE-ID: CVE-2021-22898
CWE-ID:
CWE-457 - Use of Uninitialized Variable
Exploit availability: No
DescriptionThe 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)Update the affected packages.
net-misc/curl to version: 7.77.0
Gentoo Linux: All versions
CPE2.3 External linkshttp://security.gentoo.org/
http://security.gentoo.org/glsa/202105-36
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
4) Use-after-free
EUVDB-ID: #VU53589
Risk: High
CVSSv3.1: 7.1 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]
CVE-ID: CVE-2021-22901
CWE-ID:
CWE-416 - Use After Free
Exploit availability: No
DescriptionThe 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.
MitigationUpdate the affected packages.
net-misc/curl to version: 7.77.0
Gentoo Linux: All versions
CPE2.3 External linkshttp://security.gentoo.org/
http://security.gentoo.org/glsa/202105-36
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
