CVE-2021-21703
What it is
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.
At a glance
- Exploitability
- Can be exploited locally on the machine with a low-privilege account. High risk of data exposure, data tampering, service disruption.
- Exploit odds
- 1.4% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 1.4% in the next 30 days (EPSS).
- Severity: 7.8 HIGH (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 1.4% · EPSS, next 30 days
- Weakness
- CWE-284 · Improper access control
- Record status
- Modified
Affected
- PHP ≤ 7.3.31
- PHP < 7.4.25
- PHP < 8.0.12
- Debian Linux 9.0
- Debian Linux 10.0
- Debian Linux 11.0
- Fedoraproject Fedora 33
- Fedoraproject Fedora 34
Attack profile CVSS 3.1 · 7.8
- Attack vector
- Local
- Complexity
- High
- Privileges needed
- Low
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Raw vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2021-21703.md and follow it. Check whether this project is affected by CVE-2021-21703. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- http://www.openwall.com/lists/oss-security/2021/10/26/7
- https://bugs.php.net/bug.php?id=81026
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://www.oracle.com/security-alerts/cpujan2022.html
- http://www.openwall.com/lists/oss-security/2021/10/26/7
- https://bugs.php.net/bug.php?id=81026
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://www.oracle.com/security-alerts/cpujan2022.html
References
- http://www.openwall.com/lists/oss-security/2021/10/26/7
- https://bugs.php.net/bug.php?id=81026
- https://lists.debian.org/debian-lts-announce/2021/10/msg00021.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6PZVLICZUJMXOGWOUWSBAEGIVTF6Y6V3/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JO5RA6YOBGGGKLIA6F6BQRZDDECF5L3R/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PBM3KKB3RY2YPOKNMC4HIH7IH3T3WC74/
- https://security.gentoo.org/glsa/202209-20
- https://security.netapp.com/advisory/ntap-20211118-0003/
- https://www.debian.org/security/2021/dsa-4992
- https://www.debian.org/security/2021/dsa-4993
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://www.oracle.com/security-alerts/cpujan2022.html
- http://www.openwall.com/lists/oss-security/2021/10/26/7
- https://bugs.php.net/bug.php?id=81026
- https://lists.debian.org/debian-lts-announce/2021/10/msg00021.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6PZVLICZUJMXOGWOUWSBAEGIVTF6Y6V3/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JO5RA6YOBGGGKLIA6F6BQRZDDECF5L3R/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PBM3KKB3RY2YPOKNMC4HIH7IH3T3WC74/
- https://security.gentoo.org/glsa/202209-20
- https://security.netapp.com/advisory/ntap-20211118-0003/
- https://www.debian.org/security/2021/dsa-4992
- https://www.debian.org/security/2021/dsa-4993
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://www.oracle.com/security-alerts/cpujan2022.html