CVE-2017-8820 Null dereference 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

What is CVE-2017-8820?

CVE-2017-8820 is a high-severity vulnerability in Debian Debian Linux, published on 3 Dec 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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, remote attackers can cause a denial of service (NULL pointer dereference and application crash) against directory authorities via a malformed descriptor, aka TROVE-2017-010.

Weakness: CWE-476

Which versions are affected by CVE-2017-8820?

It affects 2 products.

Products include Debian Debian Linux, Tor Project Tor.

How do I fix CVE-2017-8820?

Upgrade to a fixed version.

Is CVE-2017-8820 being exploited?

There is no known exploitation of CVE-2017-8820 in the wild and no public exploit code.

Other vulnerabilities in Debian Debian Linux

• CVE-2015-3306 ProFTPD Improper Access Control Exploited Critical 10.0
• CVE-2025-49113 RoundCube Webmail Deserialization of Untrusted Data Exploited Critical 9.9
• CVE-2026-24061 GNU InetUtils Argument Injection Exploited Critical 9.8
• CVE-2025-39682 Linux Kernel Improper Check for Unusual or Exceptional Conditions Exploited Critical 9.8
• CVE-2024-9680 Mozilla Firefox Use-After-Free Exploited Critical 9.8

All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2017-8820, GHSA-rcr7-p7pf-h84m, UBUNTU-CVE-2017-8820.