CVE-2019-20633 Use after free in n/a

Medium 5.5 Published 25 Mar 2020 Updated 5 Aug 2024

A double-free vulnerability in GNU patch allows attackers to cause a denial of service via a crafted patch file.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: A user has to click or open something
Fix: Available

What is CVE-2019-20633?

CVE-2019-20633 is a medium-severity use after free vulnerability in n/a, published on 25 Mar 2020. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

Official description

GNU patch through 2.7.6 contains a free(p_line[p_end]) Double Free vulnerability in the function another_hunk in pch.c that can cause a denial of service via a crafted patch file. NOTE: this issue exists because of an incomplete fix for CVE-2018-6952.

Weakness: CWE-415

Which versions are affected by CVE-2019-20633?

It affects 1 product.

Linux distribution packages (8)

`patch` SUSE:Linux Enterprise Module for Basesystem 15 SP5	All versions	`2.7.6-150000.5.6.1`
`patch` SUSE:Linux Enterprise Module for Basesystem 15 SP6	All versions	`2.7.6-150000.5.6.1`
`patch` SUSE:Linux Enterprise Server 12 SP5	All versions	`2.7.5-8.11.1`
`patch` SUSE:Linux Enterprise Server for SAP Applications 12 SP5	All versions	`2.7.5-8.11.1`
`patch` SUSE:Linux Micro 6.0	All versions	`2.7.6-3.1`
`patch` openSUSE:Leap 15.5	All versions	`2.7.6-150000.5.6.1`
`patch` openSUSE:Leap 15.6	All versions	`2.7.6-150000.5.6.1`
`patch` openSUSE:Tumbleweed	All versions	`2.7.6-8.1`

Products include Gnu Patch.

How do I fix CVE-2019-20633?

Apply the vendor's patch.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2019-20633 being exploited?

There is no known exploitation of CVE-2019-20633 in the wild and no public exploit code.

Sources

Also known as ALPINE-CVE-2019-20633, AZL-35107, AZL-6791, CLEANSTART-2026-KM86582, GHSA-w88p-xvmw-fxgg, JLSEC-2026-18 and 5 more.