CVE-2023-26437 | Deterred spoofing attempts can lead to authoritative servers being marked unavailable

Denial of service vulnerability in PowerDNS Recursor allows authoritative servers to be marked unavailable.This issue affects Recursor: through 4.6.5, through 4.7.4 , through 4.8.3.

Published: 2023-04-04 Last update: 2025-02-13 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-26437 is rated Low Risk (14.5/100): CVSS Low severity, with low exploitation likelihood (EPSS 0.02%). Low composite risk—no urgent action required; patch on your normal maintenance cycle and revisit priority if CVSS or EPSS increases.

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-2023-26437

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 2025-03-17 0.12% 0.02% -0.10%
2 2024-04-10 0.17% 0.12% -0.05%
3 2023-04-15 — 0.17% —

Full EPSS history (5 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-26437

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
3.4 3.1 LOW
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:N/A:L 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:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 1.6 1.4 [email protected]
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L 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:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 1.4 [email protected]

Weakness enumeration for CVE-2023-26437

OS Trackers for CVE-2023-26437

vendor priority summary link
debian end-of-life CVE-2023-26437 end-of-life priority: Debian including 1 source packages (pdns-recursor), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 4, open 1. https://security-tracker.debian.org/tracker/CVE-2023-26437
ubuntu medium CVE-2023-26437 medium priority: Ubuntu including 1 source packages (pdns-recursor), 13 status rows across 13 suites (bionic, focal, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): needs-triage 7, ignored 6. https://ubuntu.com/security/CVE-2023-26437

Affected software / configurations for CVE-2023-26437

Vendor Product Version Raw CPE
powerdns recursor < 4.6.6 cpe:2.3:a:powerdns:recursor:*:*:*:*:*:*:*:*
powerdns recursor >= 4.7.0, < 4.7.5 cpe:2.3:a:powerdns:recursor:*:*:*:*:*:*:*:*
powerdns recursor >= 4.8.0, < 4.8.4 cpe:2.3:a:powerdns:recursor:*:*:*:*:*:*:*:*

References for CVE-2023-26437

cvelogic Threat Intelligence