#VU37869 Input validation error in Tor - CVE-2017-8822

Vulnerability identifier: #VU37869

Vulnerability risk: Low

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

CVE-ID: CVE-2017-8822

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Tor
Client/Desktop applications / Web browsers

Vendor: tor.eff.org

Description

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

In Tor before 0.2.5.16, 0.2.6 through 0.2.8 before 0.2.8.17, 0.2.9 before 0.2.9.14, 0.3.0 before 0.3.0.13, and 0.3.1 before 0.3.1.9, relays (that have incompletely downloaded descriptors) can pick themselves in a circuit path, leading to a degradation of anonymity, aka TROVE-2017-012.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Tor: 0.3.1 - 0.3.1.8

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External links
https://blog.torproject.org/new-stable-tor-releases-security-fixes-0319-03013-02914-02817-02516
https://bugs.torproject.org/21534
https://bugs.torproject.org/24333
https://www.debian.org/security/2017/dsa-4054

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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.