Is CVE-2021-21703 being actively exploited?

It is not currently in CISA's KEV catalog. Its EPSS exploitation probability is 1%.

What products does CVE-2021-21703 affect?

Tracked products affected include PHP. Check the version you run to see whether it is affected.

How do I fix CVE-2021-21703?

Apply the vendor fix promptly. An official patch or advisory is available. Upgrade affected products to a fixed version.

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CVE-2021-21703

Q: What is CVE-2021-21703?

CVE-2021-21703 is a high-severity software vulnerability (Improper access control) with a CVSS score of 7.8. 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

HIGH severity · CVSS 7.8 · Improper access control

7.8CVSS HIGH

Summary

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.

Impact & exploitability

Attack vectorLocal

Attack complexityHigh

Privileges requiredLow

User interactionNone

Confidentiality impactHigh

Integrity impactHigh

Availability impactHigh

Exploit probability (EPSS)1%

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

Affected products we track (1)

PHP

Recommendation

Apply the vendor fix promptly. Open any affected product above for its exact safe version.

Official patch: http://www.openwall.com/lists/oss-security/2021/10/26/7 ↗

CVE-2021-21703

Summary

Impact & exploitability

Affected products we track (1)

Recommendation

Additional information