CVE-2021-36754
HighExploitedPowerDNS Authoritative Server 4.5.0 before 4.5.1 allows anybody to crash the process by sending a specific query (QTYPE 65535) that causes an out-of-bounds exception.
Published Jul 27, 2021 · Updated Aug 7, 2026
Key Facts
Patch immediately- CVE-2021-36754 is a high-severity vulnerability (CVSS 7.5 v3.1) affecting Authoritative Server (Powerdns), powerdns (arch), pdns (alpine) and 9 more products.
- It is exploited in the wild, listed in Industry KEV feed since Oct 20, 2025. No public exploit code is known.
- EPSS estimates a 65% probability of exploitation in the next 30 days.
- Fixed versions are available, including pdns 4.5.1-1.5, pdns 4.5.1-r0, pdns-backend-geoip 4.5.1-1.5.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS (30-day exploit likelihood)
65%
Higher than 99.2% of all scored CVEs
Exploited in the wild
Yes
1 catalog listing
Public exploit code
None known
Get the full CVE-2021-36754 brief as a PDF
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Description
PowerDNS Authoritative Server 4.5.0 before 4.5.1 allows anybody to crash the process by sending a specific query (QTYPE 65535) that causes an out-of-bounds exception.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| Industry KEV feed | Oct 20, 2025 | n/a | Not reported |
Required action: Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.
Affected Products
28 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Authoritative ServerPowerdns | See advisory | 4.5.1 |
| powerdnsarch | See advisory | 4.5.1-1 |
| pdnsalpine | See advisory | 4.5.1-r0 |
| pdns-backend-geoipsuse | See advisory | 4.5.1-1.5 |
| pdns-backend-godbcsuse | See advisory | 4.5.1-1.5 |
Patched Releases
pdns
4.5.1-1.5, 4.5.1-r0
pdns-backend-geoip
4.5.1-1.5
pdns-backend-godbc
4.5.1-1.5
pdns-backend-ldap
4.5.1-1.5
pdns-backend-lmdb
4.5.1-1.5
pdns-backend-lua
4.5.1-1.5
pdns-backend-mysql
4.5.1-1.5
pdns-backend-postgresql
4.5.1-1.5
pdns-backend-remote
4.5.1-1.5
pdns-backend-sqlite3
4.5.1-1.5
powerdns
4.5.1-1
Authoritative Server
4.5.1
Timeline
Publicly disclosed
Jul 27, 2021
Added to Industry KEV feed
Oct 20, 2025
Last updated
Aug 7, 2026
Weakness Type
- CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer
References
- advisoryhttps://doc.powerdns.com/authoritative/security-advisories/index.html
- advisoryhttps://doc.powerdns.com/authoritative/security-advisories/powerdns-advisory-2021-01.html
- advisory[oss-security] 20210726 security advisory 2021-01 for PowerDNS Authoritative Server 4.5.0
- exploitVulnCheck exploitation report
FAQ
Common Questions.
PowerDNS Authoritative Server 4.5.0 before 4.5.1 allows anybody to crash the process by sending a specific query (QTYPE 65535) that causes an out-of-bounds exception.
Affected: Authoritative Server (Powerdns); powerdns (arch); pdns (alpine), among others. The full list is in the CVE brief.
It is exploited in the wild, listed in Industry KEV feed since Oct 20, 2025.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including pdns 4.5.1-1.5, pdns 4.5.1-r0, pdns-backend-geoip 4.5.1-1.5.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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