CVE-2021-23437

Name: CVE-2021-23437
Creator: NVD / NIST
Published: 2021-09-03T16:15:08.317+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 2.88%

Last modified Jun 17, 2026

CVE-2021-23437 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. The package pillow 5.2.0 and before 8.3.2 are vulnerable to Regular Expression Denial of Service (ReDoS) via the getrgb function.. EPSS estimates a 2.88% chance of exploitation in the next 30 days.

Description

The package pillow 5.2.0 and before 8.3.2 are vulnerable to Regular Expression Denial of Service (ReDoS) via the getrgb function.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

2.88%

85.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-125

Affected Software

Vendor	Product	Versions
Python	Pillow	>= 5.2.0, < 8.3.2
Fedoraproject	Fedora	33
Fedoraproject	Fedora	34

References

https://github.com/python-pillow/Pillow/commit/9e08eb8f78fdfd2f476e1b20b7cf38683754866bPatch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2024/03/msg00021.html
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RNSG6VFXTAROGF7ACYLMAZNQV4EJ6I2C/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VKRCL7KKAKOXCVD7M6WC5OKFGL4L3SJT/
https://pillow.readthedocs.io/en/stable/releasenotes/8.3.2.htmlRelease Notes, Vendor Advisory
https://security.gentoo.org/glsa/202211-10Third Party Advisory
https://snyk.io/vuln/SNYK-PYTHON-PILLOW-1319443Exploit, Patch, Release Notes, Third Party Advisory
https://github.com/python-pillow/Pillow/commit/9e08eb8f78fdfd2f476e1b20b7cf38683754866bPatch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2024/03/msg00021.html
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RNSG6VFXTAROGF7ACYLMAZNQV4EJ6I2C/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VKRCL7KKAKOXCVD7M6WC5OKFGL4L3SJT/
https://pillow.readthedocs.io/en/stable/releasenotes/8.3.2.htmlRelease Notes, Vendor Advisory
https://security.gentoo.org/glsa/202211-10Third Party Advisory
https://snyk.io/vuln/SNYK-PYTHON-PILLOW-1319443Exploit, Patch, Release Notes, Third Party Advisory

Timeline

Published: Sep 3, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-23437?

The package pillow 5.2.0 and before 8.3.2 are vulnerable to Regular Expression Denial of Service (ReDoS) via the getrgb function.

How severe is CVE-2021-23437?

CVE-2021-23437 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 2.88% probability of exploitation in the next 30 days.

How do I fix CVE-2021-23437?

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.

Are you affected by CVE-2021-23437?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST