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TI-2026-15894 Aliases CVE-2026-19538GHSA-q27j-h4qm-x5f7

Bypass of BLOCKED ACL items on proxy protocol port over TCP or TLS

Priority LOW 36CWE-290Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
Present
Impact type
Security bypass
Confidentiality · integrity · availability
High · None · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-290.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0044 38th percentileScored 2026-11-07
Fix Fixed NSD (NLnet Labs): 4.15.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
NLnet LabsNSD4.8.0 to before 4.15.14.15.1Patch availableCNA
  • NSD VendorNLnet Labs Affected 4.8.0 to before 4.15.1 Fixed in 4.15.1 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:nlnetlabs:nsd:*:*:*:*:*:*:*:*4.8.0 to before 4.15.1VulnerableNLNETLABS
  • cpe:2.3:a:nlnetlabs:nsd:*:*:*:*:*:*:*:* Versions 4.8.0 to before 4.15.1 Vulnerable ·NLNETLABS

Remediation

  • Fix · CNA NSD (NLnet Labs) Fixed in 4.15.1

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    NLnet Labs NSD 4.15.1

    4 records Highest priority Priority LOW 4 LOW

    Other records, highest priority first

    • TI-2026-15468 Remote TCP DoS by throttling the TCP receive windowPriority LOW 37
    • TI-2026-15825 Remote UDP DoS by sending multiple DNS Cookie optionsPriority LOW 36
    • TI-2026-15293 Wrong interpretation of ACL rangesPriority LOW 36
    Show all 4 records →

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-19538
  2. 2026-10-03 Alias added: GHSA-q27j-h4qm-x5f7

References

Advisory 1

  • TI-2026-25690 Possible arbitrary code execution during DNSSEC validation CVSS 4.0CRITICAL 9.1
  • TI-2026-56302 Heap buffer overflow and possible Remote Code Execution when digesting DNSKEY CVSS 4.0CRITICAL 9.1
  • TI-2026-31146 Crash during DNSSEC validation of malicious content CVSS 4.0HIGH 8.7
  • TI-2026-31135 Heap overflow with multiple NSID, COOKIE, PADDING EDNS options CVSS 4.0HIGH 8.7
  • TI-2026-36436 Routinator crashes on specifically crafted RRDP XML files CVSS 4.0HIGH 8.7
  • TI-2026-36433 Routinator exits when accepting an incoming HTTP or RTR connection fails CVSS 4.0HIGH 8.7
See all 96 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences