Gentoo update for Tor

Published: 2021-07-10

Risk	Medium
Patch available	YES
Number of vulnerabilities	5
CVE-ID	CVE-2021-28089 CVE-2021-28090 CVE-2021-34548 CVE-2021-34549 CVE-2021-34550
CWE-ID	CWE-400 CWE-617 CWE-200 CWE-399 CWE-125
Exploitation vector	Network
Public exploit	N/A
Vulnerable software Subscribe	Gentoo Linux Operating systems & Components / Operating system
Vendor	Gentoo

Security Bulletin

This security bulletin contains information about 5 vulnerabilities.

1) Resource exhaustion

EUVDB-ID: #VU51541

Risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-28089

CWE-ID: CWE-400 - Resource exhaustion

Exploit availability: No

Description

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

The vulnerability exists due to application does not properly control consumption of internal resources when processing directory data. A remote attacker can force the Tor instance do consume huge amounts of CPU resources and perform a denial of service (DoS) attack.

Mitigation

Update the affected packages.
net-vpn/tor to version: 0.4.6.5

Vulnerable software versions

Gentoo Linux: All versions

External links

http://security.gentoo.org/
http://security.gentoo.org/glsa/202107-25

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) Reachable Assertion

EUVDB-ID: #VU51542

Risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-28090

CWE-ID: CWE-617 - Reachable Assertion

Exploit availability: No

Description

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

The vulnerability exists due to a reachable assertion in servers configured as directory authorities. A remote attacker can send specially crafted data to the server, trigger an assertions failure and crash it.

Mitigation

Update the affected packages.
net-vpn/tor to version: 0.4.6.5

Vulnerable software versions

Gentoo Linux: All versions

External links

http://security.gentoo.org/
http://security.gentoo.org/glsa/202107-25

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) Information disclosure

EUVDB-ID: #VU54229

Risk: Medium

CVSSv3.1: 4.6 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-34548

CWE-ID: CWE-200 - Information exposure

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform spoofing attack.

The vulnerability exists due to incorrect processing of user-supplied data. A remote attacker can spoof RELAY_END or RELAY_RESOLVED cell on half-closed streams, which would allow a relay on a circuit to end a stream that wasn't actually built with it.

Mitigation

Update the affected packages.
net-vpn/tor to version: 0.4.6.5

Vulnerable software versions

Gentoo Linux: All versions

External links

http://security.gentoo.org/
http://security.gentoo.org/glsa/202107-25

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) Resource management error

EUVDB-ID: #VU54230

Risk: Low

CVSSv3.1: 3.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-34549

CWE-ID: CWE-399 - Resource Management Errors

Exploit availability: No

Description

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

The vulnerability exists due to improper management of internal resources within the naive unkeyed hash function. A remote attacker can construct circuits with chosen circuit IDs, to create collisions and make the hash table inefficient, resulting in denial of service condition.

Mitigation

Update the affected packages.
net-vpn/tor to version: 0.4.6.5

Vulnerable software versions

Gentoo Linux: All versions

External links

http://security.gentoo.org/
http://security.gentoo.org/glsa/202107-25

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.

5) Out-of-bounds read

EUVDB-ID: #VU54231

Risk: Low

CVSSv3.1: 3.8 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-34550

CWE-ID: CWE-125 - Out-of-bounds read

Exploit availability: No

Description

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

The vulnerability exists due to a boundary condition during v3 onion service descriptor parsing. A remote attacker can create an onion service descriptor that would crash any client that tried to visit it.

Mitigation

Update the affected packages.
net-vpn/tor to version: 0.4.6.5

Vulnerable software versions

Gentoo Linux: All versions

External links

http://security.gentoo.org/
http://security.gentoo.org/glsa/202107-25

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.