CVE-2021-23017A security issue in nginx resolver was identified, which might allow an attacker who is able to forge UDP packets from the DNS server to…
- 7.7HighCVSS base score
- 53.5%Exploitation in 30 daysEPSS · top 1.0% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- 1Public exploitsMetasploit, Nuclei and Exploit-DB
Description
A security issue in nginx resolver was identified, which might allow an attacker who is able to forge UDP packets from the DNS server to cause 1-byte memory overwrite, resulting in worker process crash or potential other impact.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. The public collections list an Exploit-DB entry for it.
Show the exploits1
Exploit-DB1 entry
- Nginx 1.20.0 - Denial of Service (DOS) (Exploit-DB entry) (opens in a new tab)
EDB-ID 50973remote, multiplepublished 11 Jul 2022Not verified
Modules, templates and exploits as listed by the Metasploit Framework (BSD-3-Clause), ProjectDiscovery's Nuclei templates (MIT) and the Exploit Database (GPLv2), read once a day. Where the data comes from
Timeline
ID reserved
By f5
- 5 months later
· 5 months later
Published
- 3 years later
· 3 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | High7.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L |
- EPSS (exploitation in 30 days)
- 53.5% · top 1.0% of all CVEs (13 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.7.
Affected products
Nginx Web Server, Nginx Plus
- affected Nginx Web Server versions 0.6.18 thru 1.20.0 before 1.20.1, Nginx plus versions R13 thru R23 before R23 P1. Nginx plus version R24 before R24 P1
References
References14
- https://support.f5.com/csp/article/K12331123%2C (opens in a new tab)x_refsource_MISCx_transferred
- http://mailman.nginx.org/pipermail/nginx-announce/2021/000300.html (opens in a new tab)x_refsource_MISCx_transferred
- [apisix-notifications] 20210607 [GitHub] [apisix-website] Serendipity96 opened a new pull request #362: feat: add new blog (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- [apisix-notifications] 20210608 [GitHub] [apisix-website] liuxiran commented on a change in pull request #362: docs: added "Apache APISIX not affected by NGINX CVE-2021-23017" (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- [apisix-notifications] 20210608 [GitHub] [apisix-website] netlify[bot] edited a comment on pull request #362: docs: added "Apache APISIX not affected by NGINX CVE-2021-23017" (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- [apisix-notifications] 20210608 [GitHub] [apisix-website] liuxiran merged pull request #362: docs: added "Apache APISIX not affected by NGINX CVE-2021-23017" (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- [apisix-notifications] 20210608 [apisix-website] branch master updated: docs: added "Apache APISIX not affected by NGINX CVE-2021-23017" (#362) (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- FEDORA-2021-b37cffac0d (opens in a new tab)vendor-advisoryx_refsource_FEDORAx_transferred
- FEDORA-2021-393d698493 (opens in a new tab)vendor-advisoryx_refsource_FEDORAx_transferred
- https://www.oracle.com/security-alerts/cpuoct2021.html (opens in a new tab)x_refsource_MISCx_transferred
- https://security.netapp.com/advisory/ntap-20210708-0006/ (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://www.oracle.com/security-alerts/cpujan2022.html (opens in a new tab)x_refsource_MISCx_transferred
- https://www.oracle.com/security-alerts/cpuapr2022.html (opens in a new tab)x_refsource_MISCx_transferred
- http://packetstormsecurity.com/files/167720/Nginx-1.20.0-Denial-Of-Service.html (opens in a new tab)x_refsource_MISCx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2021-10135 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2021-23017)Record last updated .