CVE-2023-50387

Certain DNSSEC aspects of the DNS protocol (in RFC 4033, 4034, 4035, 6840, and related RFCs) allow remote attackers to cause a denial of service (CPU consumption) via one or more DNSSEC responses, aka the "KeyTrap" issue. One of the concerns is that, when there is a zone with many DNSKEY and RRSIG records, the protocol specification implies that an algorithm must evaluate all combinations of DNSKEY and RRSIG records.

Published: 2024-02-14 Last update: 2025-11-04 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-50387 is rated Moderate Risk (64.6/100): CVSS High severity, with high exploitation likelihood (EPSS 43.70%, 98th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-50387

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-27 43.21% 43.70% +0.49%
2 2026-05-22 51.99% 43.21% -8.77%
3 2026-03-20 — 51.99% —

Full EPSS history (79 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-50387

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2023-50387

OS Trackers for CVE-2023-50387

vendor priority summary link
alpine — CVE-2023-50387: 5 source package rows (bind, dnsmasq, knot-resolver, pdns-recursor, unbound); 31 state rows across 12 repos (3.17-main, 3.18-main, 3.19-community, 3.19-main, 3.20-community, 3.20-main, 3.21-community, 3.21-main, 3.22-community, 3.22-main, edge-community, edge-main); fixed 31, open 0. https://security.alpinelinux.org/vuln/CVE-2023-50387
debian end-of-life CVE-2023-50387 end-of-life priority: Debian including 7 source packages (bind9, dnsjava, …), 35 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 31, open 4. https://security-tracker.debian.org/tracker/CVE-2023-50387
gentoo normal CVE-2023-50387: 1 GLSA(s) (202412-10), 1 atom(s) (net-dns/dnsmasq); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2023-50387
redhat high — https://access.redhat.com/security/cve/CVE-2023-50387
suse high — https://www.suse.com/security/cve/CVE-2023-50387/
ubuntu medium CVE-2023-50387 medium priority: Ubuntu including 7 source packages (bind9, bind9-libs, …), 77 status rows across 11 suites (bionic, focal, jammy, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): released 31, needs-triage 17, not-affected 14, DNE 9, ignored 6. https://ubuntu.com/security/CVE-2023-50387

Affected software / configurations for CVE-2023-50387

Vendor Product Version Raw CPE
redhat enterprise_linux 6.0 cpe:2.3:o:redhat:enterprise_linux:6.0:*:*:*:*:*:*:*
redhat enterprise_linux 7.0 cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
redhat enterprise_linux 8.0 cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
redhat enterprise_linux 9.0 cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*
microsoft windows_server_2008 r2 cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:*:*:*:*:x64:*
microsoft windows_server_2012 — cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:*
microsoft windows_server_2012 r2 cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:*
microsoft windows_server_2016 — cpe:2.3:o:microsoft:windows_server_2016:-:*:*:*:*:*:*:*
microsoft windows_server_2019 — cpe:2.3:o:microsoft:windows_server_2019:-:*:*:*:*:*:*:*
microsoft windows_server_2022 — cpe:2.3:o:microsoft:windows_server_2022:-:*:*:*:*:*:*:*
microsoft windows_server_2022_23h2 — cpe:2.3:o:microsoft:windows_server_2022_23h2:-:*:*:*:*:*:*:*
fedoraproject fedora 39 cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:*
thekelleys dnsmasq < 2.90 cpe:2.3:a:thekelleys:dnsmasq:*:*:*:*:*:*:*:*
nic knot_resolver < 5.71 cpe:2.3:a:nic:knot_resolver:*:*:*:*:*:*:*:*
powerdns recursor >= 4.8.0, < 4.8.6 cpe:2.3:a:powerdns:recursor:*:*:*:*:*:*:*:*
powerdns recursor >= 4.9.0, < 4.9.3 cpe:2.3:a:powerdns:recursor:*:*:*:*:*:*:*:*
powerdns recursor >= 5.0.0, < 5.0.2 cpe:2.3:a:powerdns:recursor:*:*:*:*:*:*:*:*
isc bind >= 9.0.0, <= 9.16.46 cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*
isc bind >= 9.18.0, <= 9.18.22 cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*
isc bind >= 9.19.0, <= 9.19.20 cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*
nlnetlabs unbound < 1.19.1 cpe:2.3:a:nlnetlabs:unbound:*:*:*:*:*:*:*:*

References for CVE-2023-50387

URL Tags
http://www.openwall.com/lists/oss-security/2024/02/16/2 Mailing List
http://www.openwall.com/lists/oss-security/2024/02/16/3 Mailing List
https://access.redhat.com/security/cve/CVE-2023-50387 Third Party Advisory
https://bugzilla.suse.com/show_bug.cgi?id=1219823 Issue Tracking
https://docs.powerdns.com/recursor/security-advisories/powerdns-advisory-2024-01.html Third Party Advisory
https://gitlab.nic.cz/knot/knot-resolver/-/releases/v5.7.1 Patch
https://kb.isc.org/docs/cve-2023-50387 Third Party Advisory VDB Entry
https://lists.debian.org/debian-lts-announce/2024/02/msg00006.html
https://lists.debian.org/debian-lts-announce/2024/05/msg00011.html
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6FV5O347JTX7P5OZA6NGO4MKTXRXMKOZ/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BUIP7T7Z4T3UHLXFWG6XIVDP4GYPD3AI/ Mailing List
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HVRDSJVZKMCXKKPP6PNR62T7RWZ3YSDZ/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IGSLGKUAQTW5JPPZCMF5YPEYALLRUZZ6/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PNNHZSZPG2E7NBMBNYPGHCFI4V4XRWNQ/ Mailing List
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RGS7JN6FZXUSTC2XKQHH27574XOULYYJ/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SVYA42BLXUCIDLD35YIJPJSHDIADNYMP/ Mailing List
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TEXGOYGW7DBS3N2QSSQONZ4ENIRQEAPG/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UQESRWMJCF4JEYJEAKLRM6CT55GLJAB7/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZDZFMEKQTZ4L7RY46FCENWFB5MDT263R/
https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2024q1/017430.html Mailing List Third Party Advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-50387 Patch Vendor Advisory
https://news.ycombinator.com/item?id=39367411 Third Party Advisory
https://news.ycombinator.com/item?id=39372384 Issue Tracking
https://nlnetlabs.nl/news/2024/Feb/13/unbound-1.19.1-released/ Vendor Advisory
https://security.netapp.com/advisory/ntap-20240307-0007/
https://www.athene-center.de/aktuelles/key-trap Third Party Advisory
https://www.athene-center.de/fileadmin/content/PDF/Technical_Report_KeyTrap.pdf Technical Description Third Party Advisory
https://www.isc.org/blogs/2024-bind-security-release/ Third Party Advisory
https://www.securityweek.com/keytrap-dns-attack-could-disable-large-parts-of-internet-researchers/ Press/Media Coverage Third Party Advisory
https://www.theregister.com/2024/02/13/dnssec_vulnerability_internet/ Patch Third Party Advisory
https://lists.debian.org/debian-lts-announce/2024/09/msg00001.html
https://lists.debian.org/debian-lts-announce/2024/11/msg00035.html
https://lists.fedoraproject.org/archives/list/[email protected]/message/BUIP7T7Z4T3UHLXFWG6XIVDP4GYPD3AI/
https://lists.fedoraproject.org/archives/list/[email protected]/message/HVRDSJVZKMCXKKPP6PNR62T7RWZ3YSDZ/
https://lists.fedoraproject.org/archives/list/[email protected]/message/RGS7JN6FZXUSTC2XKQHH27574XOULYYJ/
https://lists.fedoraproject.org/archives/list/[email protected]/message/ZDZFMEKQTZ4L7RY46FCENWFB5MDT263R/
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