#VU45424 Input validation error in Tor - CVE-2011-0491

Vulnerability identifier: #VU45424

Vulnerability 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-2011-0491

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 perform service disruption.

The tor_realloc function in Tor before 0.2.1.29 and 0.2.2.x before 0.2.2.21-alpha does not validate a certain size value during memory allocation, which might allow remote attackers to cause a denial of service (daemon crash) via unspecified vectors, related to "underflow errors."

Mitigation
Install update from vendor's website.

Vulnerable software versions

Tor: 0.0.2 - 0.2.2.20

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External links
https://archives.seul.org/or/announce/Jan-2011/msg00000.html
https://blog.torproject.org/blog/tor-02129-released-security-patches
https://www.securityfocus.com/bid/45953
https://exchange.xforce.ibmcloud.com/vulnerabilities/64888
https://gitweb.torproject.org/tor.git/blob/refs/heads/release-0.2.2:/ChangeLog
https://trac.torproject.org/projects/tor/ticket/2324

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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.