CVE-2026-19538
Bypass of BLOCKED ACL items on proxy protocol port over TCP or TLS
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Bypass of BLOCKED ACL items on proxy protocol port over TCP or TLS
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.
- Record
CVE-2026-19538- CVSS 4.0
- 8.2 High
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 - Weakness
- CWE-290, CWE-672
- Updated
- 2026-11-02
EUVDEUVD-2026-66376
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.
- Record
EUVD-2026-66376- CVSS 4.0
- 8.2 High
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 - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-q27j-h4qm-x5f7
The BLOCKED access control list items that are evaluated to deny access on the the proxy protocol...
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.
- Record
GHSA-q27j-h4qm-x5f7- CVSS 4.0
- 8.2 High
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 - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Weakness
- CWE-290
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-19538- CVSS 4.0
- 8.2 High
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 - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Weakness
- CWE-290, CWE-672
- Updated
- 2026-11-02
OSV
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.
- Record
CVE-2026-19538- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Updated
- 2026-11-02
OSVDEBIAN-CVE-2026-19538
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.
- Record
DEBIAN-CVE-2026-19538- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-19538
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.
- Record
UBUNTU-CVE-2026-19538- CVSS 4.0
- 8.2 High
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 - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
nsdDebian:12 |
All versions, plus listed versions 4.10.1-14.10.1~rc2-14.10.1~rc2-24.11.0-14.11.1-1 Show 20 moreShow less4.12.0-14.12.0-24.13.0-14.13.0-24.13.0-34.13.0-44.13.0-54.13.0-64.14.0-14.14.1-14.14.2-14.14.3-14.15.0-14.15.0~rc1-14.15.1-14.15.2-14.6.1-14.7.0-14.8.0-14.9.1-1 |
None known |
nsdDebian:13 |
All versions, plus listed versions 4.12.0-14.12.0-24.13.0-14.13.0-24.13.0-3 Show 11 moreShow less4.13.0-44.13.0-54.13.0-64.14.0-14.14.1-14.14.2-14.14.3-14.15.0-14.15.0~rc1-14.15.1-14.15.2-1 |
None known |
nsdDebian:14 |
before 4.15.1-1, plus listed versions 4.12.0-14.12.0-24.13.0-14.13.0-24.13.0-3 Show 9 moreShow less4.13.0-44.13.0-54.13.0-64.14.0-14.14.1-14.14.2-14.14.3-14.15.0-14.15.0~rc1-1 |
4.15.1-1 |
nsdUbuntu:Pro:16.04:LTS |
All versions, plus listed versions 4.1.2-14.1.6-14.1.7-14.1.7-1ubuntu0.1~esm1 |
None known |
nsdUbuntu:Pro:18.04:LTS |
All versions, plus listed versions 4.1.16-1build14.1.17-14.1.17-1build14.1.17-1ubuntu0.1~esm1 |
None known |
nsdUbuntu:Pro:20.04:LTS |
All versions, plus listed versions 4.1.26-14.1.26-1build14.1.26-1ubuntu0.1~esm1 |
None known |
nsdUbuntu:Pro:22.04:LTS |
All versions, plus listed versions 4.3.5-14.3.7-14.3.8-14.3.8-1build14.3.9-14.3.9-1ubuntu0.1~esm1 |
None known |
nsdUbuntu:Pro:24.04:LTS |
All versions, plus listed versions 4.7.0-14.8.0-14.8.0-1build14.8.0-1build34.8.0-1ubuntu0.1~esm1 |
None known |
nsdUbuntu:26.10 |
All versions, plus listed versions 4.14.0-14.14.2-14.14.3-14.15.0-14.15.0-1build1 |
None known |
nsdUbuntu:Pro:26.04:LTS |
All versions, plus listed versions 4.12.0-14.13.0-64.14.0-14.14.0-1ubuntu0.1~esm1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-19538 is a high vulnerability (CVSS 8.2) in Nlnet Labs Nsd, published August 26, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.44%, the 38th percentile. Fixed in nsd 4.15.1-1.