Gentoo update for Tor



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
 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

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

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

CPE2.3 External links

https://security.gentoo.org/
https://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

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

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

CPE2.3 External links

https://security.gentoo.org/
https://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

CVSSv4.0: 2.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

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

CPE2.3 External links

https://security.gentoo.org/
https://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

CVSSv4.0: 1.7 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear]

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

CPE2.3 External links

https://security.gentoo.org/
https://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

CVSSv4.0: 1.2 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear]

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

CPE2.3 External links

https://security.gentoo.org/
https://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.



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