CVE-2026-19538

HIGH

8.2

CVSS v4

Description

The BLOCKED access control list items that are evaluated to deny access on the the proxy protocol port can be bypassed completely when connecting over TCP or TLS and sending the query twice on connection that is kept open.

CWE-290 CWE-672

How to fix

Remediation Available

nsdDebian

Fixed in:4.15.1-1CVE-2026-19538

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v4 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

Impact

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Exploit Intelligence

0.35%probability of exploitation in 30 days

28thpercentile

Low risk: more likely to be exploited than 28% of all known CVEs.

References

Other references1

nlnetlabs.nl

Related Vulnerabilities

Other CWE-290 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-4358	Critical	9.8	97%	KEV	-
CVE-2022-24112	Critical	9.8	96%	KEV	Fix
CVE-2022-23131	Critical	9.1	96%	KEV	-
CVE-2021-29441	High	8.6	88%	-	Fix
CVE-2019-1234	High	7.5	74%	-	-
CVE-2021-31195	Medium	6.5	74%	-	Fix

Common questions

How do I fix CVE-2026-19538?

Upgrade nsd on debian unstable to 4.15.1-1 or later.

Is CVE-2026-19538 being actively exploited?

Not that we know of. CVE-2026-19538 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.35% is the estimated probability that it will be exploited in the next 30 days. That is higher than 28% of all scored CVEs.

How severe is CVE-2026-19538?

CVE-2026-19538 has a CVSS v4 base score of 8.2, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-19538 affect?

Published advisories record a fix for nsd (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

Embed a live status badge for CVE-2026-19538

Markdown

[![CVE-2026-19538](https://tridentstack.com/cve/badge/CVE-2026-19538.svg)](https://tridentstack.com/cve/CVE-2026-19538)

HTML

<a href="https://tridentstack.com/cve/CVE-2026-19538"><img src="https://tridentstack.com/cve/badge/CVE-2026-19538.svg" alt="CVE-2026-19538"></a>

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

See how it works Start freeThis CVE lookup is free and always will be.

This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-26.