CVE-2018-1000030: Python 2.7.14 is vulnerable to a Heap-Buffer-Overflow as well as a Heap-Use-After-Free. Python versions prior to 2.7.14 may also be vulnerable and it ...

Description

Python 2.7.14 is vulnerable to a Heap-Buffer-Overflow as well as a Heap-Use-After-Free. Python versions prior to 2.7.14 may also be vulnerable and it appears that Python 2.7.17 and prior may also be vulnerable however this has not been confirmed. The vulnerability lies when multiply threads are handling large amounts of data. In both cases there is essentially a race condition that occurs. For the Heap-Buffer-Overflow, Thread 2 is creating the size for a buffer, but Thread1 is already writing to the buffer without knowing how much to write. So when a large amount of data is being processed, it is very easy to cause memory corruption using a Heap-Buffer-Overflow. As for the Use-After-Free, Thread3->Malloc->Thread1->Free's->Thread2-Re-uses-Free'd Memory. The PSRT has stated that this is not a security vulnerability due to the fact that the attacker must be able to run code, however in some situations, such as function as a service, this vulnerability can potentially be used by an attacker to violate a trust boundary, as such the DWF feels this issue deserves a CVE.

Metrics

CVSS 3.1

3.6/10

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:L

EPSS Probability

1.21%

64.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Python	Python	<= 2.7.14
Canonical	Ubuntu Linux	12.04
Canonical	Ubuntu Linux	14.04
Canonical	Ubuntu Linux	16.04
Canonical	Ubuntu Linux	18.04

References

https://bugs.python.org/issue31530Issue Tracking, Patch, Vendor Advisory
https://drive.google.com/file/d/1oyR9DAZjZK_SCn3mor6NRAYLJS6ueXaY/viewThird Party Advisory
https://security.gentoo.org/glsa/201811-02Third Party Advisory
https://usn.ubuntu.com/3817-1/Third Party Advisory
https://usn.ubuntu.com/3817-2/Third Party Advisory
https://www.dropbox.com/sh/sj3ee7xv55j36k7/AADwP-YfOYikBMuy32e0uvPFa?dl=0Permissions Required
https://www.oracle.com/security-alerts/cpujan2020.htmlThird Party Advisory
https://bugs.python.org/issue31530Issue Tracking, Patch, Vendor Advisory
https://drive.google.com/file/d/1oyR9DAZjZK_SCn3mor6NRAYLJS6ueXaY/viewThird Party Advisory
https://security.gentoo.org/glsa/201811-02Third Party Advisory
https://usn.ubuntu.com/3817-1/Third Party Advisory
https://usn.ubuntu.com/3817-2/Third Party Advisory
https://www.dropbox.com/sh/sj3ee7xv55j36k7/AADwP-YfOYikBMuy32e0uvPFa?dl=0Permissions Required
https://www.oracle.com/security-alerts/cpujan2020.htmlThird Party Advisory

Timeline

Published: Feb 8, 2018
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2018-1000030?

Python 2.7.14 is vulnerable to a Heap-Buffer-Overflow as well as a Heap-Use-After-Free. Python versions prior to 2.7.14 may also be vulnerable and it appears that Python 2.7.17 and prior may also be vulnerable however this has not been confirmed. The vulnerability lies when multiply threads are handling large amounts of data. In both cases there is essentially a race condition that occurs. For the Heap-Buffer-Overflow, Thread 2 is creating the size for a buffer, but Thread1 is already writing to the buffer without knowing how much to write. So when a large amount of data is being processed, it is very easy to cause memory corruption using a Heap-Buffer-Overflow. As for the Use-After-Free, Thread3->Malloc->Thread1->Free's->Thread2-Re-uses-Free'd Memory. The PSRT has stated that this is not a security vulnerability due to the fact that the attacker must be able to run code, however in some situations, such as function as a service, this vulnerability can potentially be used by an attacker to violate a trust boundary, as such the DWF feels this issue deserves a CVE.

How severe is CVE-2018-1000030?

CVE-2018-1000030 has a CVSS score of 3.6/10 (LOW severity). The EPSS model estimates a 1.21% probability of exploitation in the next 30 days.

How do I fix CVE-2018-1000030?

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.