#VU31154 Out-of-bounds read in Tor - CVE-2019-8955

Vulnerability identifier: #VU31154

Vulnerability risk: Medium

CVSSv4.0: 4.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2019-8955

CWE-ID: CWE-125

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Tor
Client/Desktop applications / Web browsers

Vendor: tor.eff.org

Description

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

The vulnerability exists due to an out-of-bounds read that occurs via memory exhaustion in the KIST cell scheduler.

Mitigation
Update to version 0.3.4.11.

Vulnerable software versions

Tor: 0.3.4.8 - 0.3.4.10

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External links
https://lists.opensuse.org/opensuse-security-announce/2019-04/msg00013.html
https://www.securityfocus.com/bid/107136
https://blog.torproject.org/new-releases-tor-0402-alpha-0358-03411-and-03312
https://trac.torproject.org/projects/tor/ticket/29168

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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.