CVE-2019-8955

Name: CVE-2019-8955
Creator: NVD / NIST
Published: 2019-02-21T23:29:00.267+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

UnknownEPSS 4.57%

Last modified Jun 17, 2026

CVE-2019-8955 is a vulnerability of currently unknown severity. In Tor before 0.3.3.12, 0.3.4.x before 0.3.4.11, 0.3.5.x before 0.3.5.8, and 0.4.x before 0.4.0.2-alpha, remote denial of service against Tor clients and relays can occur via memory exhaustion in the KIST cell scheduler.. EPSS estimates a 4.57% chance of exploitation in the next 30 days.

Description

In Tor before 0.3.3.12, 0.3.4.x before 0.3.4.11, 0.3.5.x before 0.3.5.8, and 0.4.x before 0.4.0.2-alpha, remote denial of service against Tor clients and relays can occur via memory exhaustion in the KIST cell scheduler.

Metrics

EPSS Probability

4.57%

90.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-770

Affected Software

Vendor	Product	Versions	Update
Torproject	Tor	< 0.3.3.12	—
Torproject	Tor	>= 0.3.4.8, < 0.3.4.11	—
Torproject	Tor	0.3.4.0	Alpha-Dev
Torproject	Tor	0.3.4.1	Alpha
Torproject	Tor	0.3.4.2	Alpha
Torproject	Tor	0.3.4.3	Alpha
Torproject	Tor	0.3.4.4	Rc
Torproject	Tor	0.3.4.5	Rc
Torproject	Tor	0.3.4.6	Rc
Torproject	Tor	0.3.4.7	Rc
Torproject	Tor	0.3.5.0	Alpha-Dev
Torproject	Tor	0.3.5.1	Alpha
Torproject	Tor	0.3.5.2	Alpha
Torproject	Tor	0.3.5.3	Alpha
Torproject	Tor	0.3.5.4	Alpha
Torproject	Tor	0.3.5.5	Alpha
Torproject	Tor	0.3.5.6	Rc
Torproject	Tor	0.3.5.7	—
Torproject	Tor	0.4.0.1	Alpha

References

http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00013.html
http://www.securityfocus.com/bid/107136Third Party Advisory, VDB Entry
https://blog.torproject.org/new-releases-tor-0402-alpha-0358-03411-and-03312Vendor Advisory
https://trac.torproject.org/projects/tor/ticket/29168Vendor Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00013.html
http://www.securityfocus.com/bid/107136Third Party Advisory, VDB Entry
https://blog.torproject.org/new-releases-tor-0402-alpha-0358-03411-and-03312Vendor Advisory
https://trac.torproject.org/projects/tor/ticket/29168Vendor Advisory

Timeline

Published: Feb 21, 2019
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2019-8955?

How severe is CVE-2019-8955?

Severity scoring for CVE-2019-8955 is pending analysis. The EPSS model estimates a 4.57% probability of exploitation in the next 30 days.

How do I fix CVE-2019-8955?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2019-8955?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST