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Fencer Vulns
medium 5.9

CVE-2026-27138 json

Panic in name constraint checking for malformed certificates in crypto/x509

published 2026-03-06 8 mo ago modified 2026-09-08 2 mo ago also BIT-golang-2026-27138 , EUVD-2026-10086 , GO-2026-4600

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 32%
public exploits
0
none known

Summary

Certificate verification can panic when a certificate in the chain has an empty DNS name and another certificate in the chain has excluded name constraints. This can crash programs that are either directly verifying X.509 certificate chains, or those that use TLS.

Patch / fix

  • bitnami golang 1.26.1
  • go stdlib 1.26.1
  • Go standard library crypto/x509 1.26.1
  • golang-1.26 Debian 14 1.26.1-1

debian advisories DEBIAN-CVE-2026-27138

  • golang1.26 hummingbird 1 1.26.2-1.hum1
  • golang1.26-bin hummingbird 1 1.26.2-1.hum1
  • golang1.26-src hummingbird 1 1.26.2-1.hum1
  • golang1.26-misc hummingbird 1 1.26.2-1.hum1
  • golang1.26-tests hummingbird 1 1.26.2-1.hum1
  • golang1.26-shared hummingbird 1 1.26.2-1.hum1

red hat advisories RHSA-2026:7291

  • go1.26-openssl SLES for SAP applications 16.0, SLES 16.0 1.26.1-160000.1.1
  • govulncheck-vulndb openSUSE Leap 15.6 0.0.20260317T205859-150000.1.152.1
  • go1.26-openssl SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +5 more 1.26.1-150000.1.3.1
  • go1.26-openssl SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Development Tools 15 SP7 +1 more 1.26.1-150600.13.3.1
  • go1.26 SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +9 more 1.26.1-150000.1.6.1

suse advisories SUSE-SU-2026:21195-1SUSE-SU-2026:1042-1SUSE-SU-2026:0993-1SUSE-SU-2026:0976-1SUSE-SU-2026:0876-1

  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1
  • go1.26-openssl openSUSE Leap 16.0 1.26.1-160000.1.1
  • steampipe openSUSE Tumbleweed 2.4.1-1.1
  • go1.26 openSUSE Leap 16.0 1.26.1-160000.1.1
  • go1.26 openSUSE Tumbleweed 1.26.1-1.1

opensuse advisories openSUSE-SU-2026:21483-1openSUSE-SU-2026:20537-1openSUSE-SU-2026:10509-1openSUSE-SU-2026:20342-1openSUSE-SU-2026:10299-1

  • go Alpine 3.24 1.25.8-r0
  • rclone Alpine 3.24 1.73.5-r0

alpine advisories ALPINE-CVE-2026-27138

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • golang Azure Linux 3.0 1.25.8-1
  • golang Azure Linux 3.0 1.26.1-1

azure linux advisories AZL-79610AZL-79625

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-27138 updated cvss 3.7

crypto/x509: Panic in name constraint checking for malformed certificates in crypto/x509

  • Red Hat OpenShift Service Mesh 2 openshift-service-mesh/openshift-golang-builder Red Hat OpenShift Service Mesh 3 openshift-service-mesh/openshift-golang-builder Red Hat Enterprise Linux 8 golang, go-toolset, golang-bin, golang-src, golang-misc, golang-race, +1 more Red Hat Enterprise Linux 9 golang, go-toolset, golang-bin, golang-src, golang-misc, golang-race, +1 more Red Hat Enterprise Linux 10 golang Red Hat Enterprise Linux AI (RHEL AI) 3 golang
    +2 more products
    Red Hat OpenShift Container Platform 4 openshift-service-mesh/openshift-golang-builder Red Hat OpenShift Virtualization 4 openshift-service-mesh/openshift-golang-builder
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Hardened Images golang1.26 1.26.2-1.hum1, golang1.26-bin 1.26.2-1.hum1, golang1.26-src 1.26.2-1.hum1, golang1.26-misc 1.26.2-1.hum1, golang1.26-tests 1.26.2-1.hum1, golang1.26-shared 1.26.2-1.hum1
    fixed: vendor fix RHSA-2026:7291
  • Red Hat OpenShift AI 3.4 rhai/base-image-neuron-rhel9 1793042008
    fixed: vendor fix RHSA-2026:91248
  • Red Hat OpenShift AI 3.5 rhai/base-image-neuron-rhel9 1793042008
    fixed: vendor fix RHSA-2026:91249

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
8 mo ago

Exploit prediction

0.38% chance of exploitation in the next 30 days, higher than 32% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
OSV 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
bitnami golang
>=1.26.0-0, <1.26.1
1.26.1
go stdlib
>=1.26.0-0, <1.26.1
1.26.1

Affected products

  • Go standard library crypto/x509

Classification

Weakness
  • CWE-295 Improper Certificate Validation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.