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Vulnerability details: VCID-yrdf-1ka4-d7ff
Vulnerability ID VCID-yrdf-1ka4-d7ff
Aliases CVE-2021-23017
Summary 1-byte memory overwrite in resolver
Status Published
Exploitability 2.0
Weighted Severity 7.3
Risk 10.0
Affected and Fixed Packages Package Details
Weaknesses (1)
CWE-193 Off-by-one Error
System Score Found at
cvssv3 8.1 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-23017.json
epss 0.79436 https://api.first.org/data/v1/epss?cve=CVE-2021-23017
epss 0.79436 https://api.first.org/data/v1/epss?cve=CVE-2021-23017
epss 0.79436 https://api.first.org/data/v1/epss?cve=CVE-2021-23017
epss 0.79436 https://api.first.org/data/v1/epss?cve=CVE-2021-23017
epss 0.79436 https://api.first.org/data/v1/epss?cve=CVE-2021-23017
epss 0.79436 https://api.first.org/data/v1/epss?cve=CVE-2021-23017
epss 0.79436 https://api.first.org/data/v1/epss?cve=CVE-2021-23017
epss 0.79436 https://api.first.org/data/v1/epss?cve=CVE-2021-23017
epss 0.79436 https://api.first.org/data/v1/epss?cve=CVE-2021-23017
epss 0.79436 https://api.first.org/data/v1/epss?cve=CVE-2021-23017
epss 0.79436 https://api.first.org/data/v1/epss?cve=CVE-2021-23017
epss 0.79716 https://api.first.org/data/v1/epss?cve=CVE-2021-23017
epss 0.79716 https://api.first.org/data/v1/epss?cve=CVE-2021-23017
epss 0.79716 https://api.first.org/data/v1/epss?cve=CVE-2021-23017
epss 0.79716 https://api.first.org/data/v1/epss?cve=CVE-2021-23017
epss 0.80961 https://api.first.org/data/v1/epss?cve=CVE-2021-23017
epss 0.80961 https://api.first.org/data/v1/epss?cve=CVE-2021-23017
cvssv3.1 8.1 https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
generic_textual medium https://mailman.nginx.org/pipermail/nginx-announce/2021/000300.html
cvssv2 6.8 https://nvd.nist.gov/vuln/detail/CVE-2021-23017
cvssv3.1 7.7 https://nvd.nist.gov/vuln/detail/CVE-2021-23017
archlinux Medium https://security.archlinux.org/AVG-1987
archlinux Medium https://security.archlinux.org/AVG-1988
Reference id Reference type URL
http://mailman.nginx.org/pipermail/nginx-announce/2021/000300.html
http://packetstormsecurity.com/files/167720/Nginx-1.20.0-Denial-Of-Service.html
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-23017.json
https://api.first.org/data/v1/epss?cve=CVE-2021-23017
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-23017
https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
https://lists.apache.org/thread.html/r37e6b2165f7c910d8e15fd54f4697857619ad2625f56583802004009%40%3Cnotifications.apisix.apache.org%3E
https://lists.apache.org/thread.html/r4d4966221ca399ce948ef34884652265729d7d9ef8179c78d7f17e7f%40%3Cnotifications.apisix.apache.org%3E
https://lists.apache.org/thread.html/r6fc5c57b38e93e36213e9a18c8a4e5dbd5ced1c7e57f08a1735975ba%40%3Cnotifications.apisix.apache.org%3E
https://lists.apache.org/thread.html/rf232eecd47fdc44520192810560303073cefd684b321f85e311bad31%40%3Cnotifications.apisix.apache.org%3E
https://lists.apache.org/thread.html/rf318aeeb4d7a3a312734780b47de83cefb7e6995da0b2cae5c28675c%40%3Cnotifications.apisix.apache.org%3E
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/7SFVYHC7OXTEO4SMBWXDVK6E5IMEYMEE/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GNKOP2JR5L7KCIZTJRZDCUPJTUONMC5I/
https://mailman.nginx.org/pipermail/nginx-announce/2021/000300.html
https://nginx.org/download/patch.2021.resolver.txt
https://nginx.org/download/patch.2021.resolver.txt.asc
https://security.netapp.com/advisory/ntap-20210708-0006/
https://support.f5.com/csp/article/K12331123%2C
https://www.oracle.com/security-alerts/cpuapr2022.html
https://www.oracle.com/security-alerts/cpujan2022.html
https://www.oracle.com/security-alerts/cpuoct2021.html
1963121 https://bugzilla.redhat.com/show_bug.cgi?id=1963121
989095 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=989095
ASA-202106-36 https://security.archlinux.org/ASA-202106-36
ASA-202106-48 https://security.archlinux.org/ASA-202106-48
AVG-1987 https://security.archlinux.org/AVG-1987
AVG-1988 https://security.archlinux.org/AVG-1988
cpe:2.3:a:f5:nginx:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:f5:nginx:*:*:*:*:*:*:*:*
cpe:2.3:a:netapp:ontap_select_deploy_administration_utility:-:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:netapp:ontap_select_deploy_administration_utility:-:*:*:*:*:*:*:*
cpe:2.3:a:openresty:openresty:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:openresty:openresty:*:*:*:*:*:*:*:*
cpe:2.3:a:oracle:blockchain_platform:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:blockchain_platform:*:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_control_plane_monitor:3.4:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:communications_control_plane_monitor:3.4:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_control_plane_monitor:4.2:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:communications_control_plane_monitor:4.2:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_control_plane_monitor:4.3:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:communications_control_plane_monitor:4.3:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_control_plane_monitor:4.4:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:communications_control_plane_monitor:4.4:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_fraud_monitor:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:communications_fraud_monitor:*:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_operations_monitor:3.4:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:communications_operations_monitor:3.4:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_operations_monitor:4.2:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:communications_operations_monitor:4.2:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_operations_monitor:4.3:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:communications_operations_monitor:4.3:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_operations_monitor:4.4:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:communications_operations_monitor:4.4:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_session_border_controller:8.4:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:communications_session_border_controller:8.4:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_session_border_controller:9.0:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:communications_session_border_controller:9.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:enterprise_communications_broker:3.3.0:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:enterprise_communications_broker:3.3.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:enterprise_session_border_controller:8.4:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:enterprise_session_border_controller:8.4:*:*:*:*:*:*:*
cpe:2.3:a:oracle:enterprise_session_border_controller:9.0:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:enterprise_session_border_controller:9.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:enterprise_telephony_fraud_monitor:3.4:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:enterprise_telephony_fraud_monitor:3.4:*:*:*:*:*:*:*
cpe:2.3:a:oracle:enterprise_telephony_fraud_monitor:4.2:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:enterprise_telephony_fraud_monitor:4.2:*:*:*:*:*:*:*
cpe:2.3:a:oracle:enterprise_telephony_fraud_monitor:4.3:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:enterprise_telephony_fraud_monitor:4.3:*:*:*:*:*:*:*
cpe:2.3:a:oracle:enterprise_telephony_fraud_monitor:4.4:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:enterprise_telephony_fraud_monitor:4.4:*:*:*:*:*:*:*
cpe:2.3:a:oracle:goldengate:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:oracle:goldengate:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
CVE-2021-23017 Exploit https://gitlab.com/exploit-database/exploitdb/-/blob/main/exploits/multiple/remote/50973.py
CVE-2021-23017 https://nvd.nist.gov/vuln/detail/CVE-2021-23017
RHSA-2021:2258 https://access.redhat.com/errata/RHSA-2021:2258
RHSA-2021:2259 https://access.redhat.com/errata/RHSA-2021:2259
RHSA-2021:2278 https://access.redhat.com/errata/RHSA-2021:2278
RHSA-2021:2290 https://access.redhat.com/errata/RHSA-2021:2290
RHSA-2021:3653 https://access.redhat.com/errata/RHSA-2021:3653
RHSA-2021:3851 https://access.redhat.com/errata/RHSA-2021:3851
RHSA-2021:3873 https://access.redhat.com/errata/RHSA-2021:3873
RHSA-2021:3925 https://access.redhat.com/errata/RHSA-2021:3925
RHSA-2021:4618 https://access.redhat.com/errata/RHSA-2021:4618
RHSA-2022:0323 https://access.redhat.com/errata/RHSA-2022:0323
USN-4967-1 https://usn.ubuntu.com/4967-1/
USN-4967-2 https://usn.ubuntu.com/4967-2/
Data source Exploit-DB
Date added July 11, 2022
Description Nginx 1.20.0 - Denial of Service (DOS)
Ransomware campaign use Unknown
Source publication date July 11, 2022
Exploit type remote
Platform multiple
Source update date July 11, 2022
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-23017.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H Found at https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: AV:N/AC:M/Au:N/C:P/I:P/A:P Found at https://nvd.nist.gov/vuln/detail/CVE-2021-23017
Exploitability (E) Access Vector (AV) Access Complexity (AC) Authentication (Au) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

high

functional

unproven

proof_of_concept

not_defined

local

adjacent_network

network

high

medium

low

multiple

single

none

none

partial

complete

none

partial

complete

none

partial

complete
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L Found at https://nvd.nist.gov/vuln/detail/CVE-2021-23017
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.99028
EPSS Score 0.79436
Published At July 30, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2025-07-31T08:03:12.581073+00:00 Nginx Importer Import https://nginx.org/en/security_advisories.html 37.0.0