CVE-2021-21703 PHP-FPM memory access in root process leading to privilege escalation
Local unprivileged users can escalate privileges to root by exploiting memory access flaws in PHP-FPM when the main process runs as root.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-21703?
CVE-2021-21703 is a high-severity vulnerability in Debian Debian Linux, published on 25 Oct 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In PHP versions 7.3.x up to and including 7.3.31, 7.4.x below 7.4.25 and 8.0.x below 8.0.12, when running PHP FPM SAPI with main FPM daemon process running as root and child worker processes running as lower-privileged users, it is possible for the child processes to access memory shared with the main process and write to it, modifying it in a way that would cause the root process to conduct invalid memory reads and writes, which can be used to escalate privileges from local unprivileged user to the root user.
Which versions are affected by CVE-2021-21703?
3 open source packages ship an affected version, including libphp, php and php-min. It affects 5 products.
| Package | Affected | Fixed in |
|---|---|---|
libphp Bitnami | From 7.3.0 | 7.3.32, 7.4.25, 8.0.12 |
php Bitnami | From 7.3.0 | 7.3.32, 7.4.25, 8.0.12 |
php-min Bitnami | From 7.3.0 | 7.3.32, 7.4.25, 8.0.12 |
Linux distribution packages (6)
php72 SUSE:Linux Enterprise Module for Web and Scripting 12 | All versions | 7.2.5-1.72.1 |
php74 SUSE:Linux Enterprise Module for Web and Scripting 12 | All versions | 7.4.6-1.27.1 |
php72 SUSE:Linux Enterprise Software Development Kit 12 SP5 | All versions | 7.2.5-1.72.1 |
php74 SUSE:Linux Enterprise Software Development Kit 12 SP5 | All versions | 7.4.6-1.27.1 |
php7 openSUSE:Tumbleweed | All versions | 7.4.25-1.1 |
php8 openSUSE:Tumbleweed | All versions | 8.0.12-1.1 |
Products include Debian Debian Linux, Fedoraproject Fedora, Netapp Clustered Data Ontap, Oracle Communications Diameter Signaling Router, Php Php.
How do I fix CVE-2021-21703?
Upgrade libphp to a fixed version for your release line: 7.3.32, 7.4.25 or 8.0.12.
Is CVE-2021-21703 being exploited?
There is no known exploitation of CVE-2021-21703 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as BIT-libphp-2021-21703, BIT-php-2021-21703, BIT-php-min-2021-21703, CLSA-2022-1645466955, CLSA-2022-1645701000, DEBIAN-CVE-2021-21703 and 13 more.