Loading vulnerability…
CVE-2026-19538 is an improper access-control vulnerability in NSD's handling of BLOCKED access-control-list items on its Proxy Protocol listener. When the listener is accessed over TCP or TLS, a client can bypass BLOCKED ACL evaluation by retaining the connection and sending the DNS query twice. NSD 4.15.1 corrects this behavior.
Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
If you can’t patch tonight, do this now.
Patch, then assume compromise.
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
11 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A network-reachable NSD vulnerability on FreeBSD that may permit high confidentiality impact according to the listed CVSS v3/v4 vectors; the precise technical flaw is not specified.
An access-control bypass vulnerability in NSD allowing an entity with TCP or TLS access to the proxy-protocol port to bypass BLOCKED access-control items.
An NSD access-control bypass affecting the proxy-protocol port over TCP or TLS, allowing parties with access to that port to bypass BLOCKED access-control entries.
An NSD access-control bypass affecting the Proxy Protocol port over TCP or TLS, allowing clients with access to that port to bypass BLOCKED access-control entries.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.