RHSA-2021:2259: Important: nginx:1.18 security update

Published Jun 7, 2021
·
Updated

nginx is a web and proxy server supporting HTTP and other protocols, with a focus on high concurrency, performance, and low memory usage. Security Fix(es): nginx: Off-by-one in ngxresolvercopy() when labels are followed by a pointer to a root domain name (CVE-2021-23017) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Affected Software

54 affected componentsFixes available
redhat/nginx<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-all-modules<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-debugsource<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-filesystem<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-http-image-filter<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-http-image-filter-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-http-perl<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-http-perl-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-http-xslt-filter<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-http-xslt-filter-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-mail<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-mail-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-stream<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-stream-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-debugsource<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-http-image-filter<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-http-image-filter-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-http-perl<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-http-perl-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-http-xslt-filter<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-http-xslt-filter-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-mail<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-mail-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-stream<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-stream-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-debugsource<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-http-image-filter<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-http-image-filter-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-http-perl<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-http-perl-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-http-xslt-filter<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-http-xslt-filter-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-mail<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-mail-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-stream<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx-mod-stream-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1
1.18.0-3.module+el8.4.0+11152+f736ed63.1
redhat/nginx<1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
redhat/nginx-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
redhat/nginx-debugsource<1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
redhat/nginx-mod-http-image-filter<1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
redhat/nginx-mod-http-image-filter-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
redhat/nginx-mod-http-perl<1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
redhat/nginx-mod-http-perl-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
redhat/nginx-mod-http-xslt-filter<1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
redhat/nginx-mod-http-xslt-filter-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
redhat/nginx-mod-mail<1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
redhat/nginx-mod-mail-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
redhat/nginx-mod-stream<1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
redhat/nginx-mod-stream-debuginfo<1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade redhat/nginx to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1
  2. Upgrade

    Upgrade redhat/nginx-all-modules to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1
  3. Upgrade

    Upgrade redhat/nginx-filesystem to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1
  4. Upgrade

    Upgrade redhat/nginx-debuginfo to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1
  5. Upgrade

    Upgrade redhat/nginx-debugsource to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1
  6. Upgrade

    Upgrade redhat/nginx-mod-http-image-filter to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1
  7. Upgrade

    Upgrade redhat/nginx-mod-http-image-filter-debuginfo to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1
  8. Upgrade

    Upgrade redhat/nginx-mod-http-perl to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1
  9. Upgrade

    Upgrade redhat/nginx-mod-http-perl-debuginfo to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1
  10. Upgrade

    Upgrade redhat/nginx-mod-http-xslt-filter to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1
  11. Upgrade

    Upgrade redhat/nginx-mod-http-xslt-filter-debuginfo to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1
  12. Upgrade

    Upgrade redhat/nginx-mod-mail to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1
  13. Upgrade

    Upgrade redhat/nginx-mod-mail-debuginfo to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1
  14. Upgrade

    Upgrade redhat/nginx-mod-stream to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1
  15. Upgrade

    Upgrade redhat/nginx-mod-stream-debuginfo to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1
  16. Upgrade

    Upgrade redhat/nginx to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
  17. Upgrade

    Upgrade redhat/nginx-debuginfo to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
  18. Upgrade

    Upgrade redhat/nginx-debugsource to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
  19. Upgrade

    Upgrade redhat/nginx-mod-http-image-filter to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
  20. Upgrade

    Upgrade redhat/nginx-mod-http-image-filter-debuginfo to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
  21. Upgrade

    Upgrade redhat/nginx-mod-http-perl to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
  22. Upgrade

    Upgrade redhat/nginx-mod-http-perl-debuginfo to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
  23. Upgrade

    Upgrade redhat/nginx-mod-http-xslt-filter to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
  24. Upgrade

    Upgrade redhat/nginx-mod-http-xslt-filter-debuginfo to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
  25. Upgrade

    Upgrade redhat/nginx-mod-mail to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
  26. Upgrade

    Upgrade redhat/nginx-mod-mail-debuginfo to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
  27. Upgrade

    Upgrade redhat/nginx-mod-stream to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
  28. Upgrade

    Upgrade redhat/nginx-mod-stream-debuginfo to a version that resolves this vulnerability.

    Fixed in 1.18.0-3.module+el8.4.0+11152+f736ed63.1.aa
  29. Upgrade

    Upgrade nginx to a version that resolves this vulnerability.

    Fixed in 1.18Patch CVE-2021-23017

Event History

Feb 27, 2026
Advisory Published
via Red Hat·05:17 PM
Data Sourced
via Red Hat·05:17 PM
RemedyDescriptionAffected Software

Frequently Asked Questions

1

What is the severity of RHSA-2021:2259?

The severity of RHSA-2021:2259 is classified as important.

2

How do I fix RHSA-2021:2259?

To fix RHSA-2021:2259, you should update nginx to version 1.18.0-3.module+el8.4.0+11152+f736ed63.1 or newer.

3

What types of software are affected by RHSA-2021:2259?

RHSA-2021:2259 affects nginx, nginx-debuginfo, nginx-debugsource, and several modules related to nginx.

4

What vulnerabilities are addressed in RHSA-2021:2259?

RHSA-2021:2259 addresses an off-by-one vulnerability in ngx_resolver_copy() related to DNS resolution.

5

Is there a recommended action for users of nginx regarding RHSA-2021:2259?

It is recommended that users of nginx upgrade to the fixed versions immediately to mitigate potential risks.

Company

Resources

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2026 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203