CVE-2026-27145
Inefficient candidate hostname parsing in crypto/x509
MEDIUM
6.5
CVSS Score
Published: June 2, 2026 at 10:01 PM UTC
Updated: September 18, 2026 at 01:17 PM UTC
35 products affected across 2 vendorsEnterprise LinuxOpenShift Container PlatformSatellite
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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.6%
SSVC
No known exploit
Description
(*x509.Certificate).VerifyHostname previously called matchHostnames in a loop over all DNS Subject Alternative Name (SAN) entries. This caused strings.Split(host, ".") to execute repeatedly on the same input hostname. With a large DNS SAN list, verification costs scaled quadratically based on the number of SAN entries multiplied by the hostname's label count. Because x509.Verify validates hostnames before building the certificate chain, this overhead occurred even for untrusted certificates.
Affected
Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.
Affected range stops below 1.25.11, so it looks safe — our inference, not a vendor statement
Affected range stops below 1.26.4, so it looks safe — our inference, not a vendor statement
Vendor states this is fixed in 1784590741 (unaffected)
Vendor states this is fixed in 1784638644 (unaffected)
Vendor states this is fixed in 1784677172 (unaffected)
Vendor states this is fixed in 1786547792 (unaffected)
Vendor states this is fixed in 1786547807 (unaffected)
Vendor states this is fixed in 1786549537 (unaffected)
Vendor states this is fixed in 1786976940 (unaffected)
Vendor states this is fixed in 1787170830 (unaffected)
Vendor states this is fixed in 1787172840 (unaffected)
Vendor states this is fixed in 1787183407 (unaffected)
Vendor states this is fixed in 1787242099 (unaffected)
Vendor states this is fixed in 1787242105 (unaffected)
Vendor states this is fixed in 1787242108 (unaffected)
Vendor states this is fixed in 1787242131 (unaffected)
Vendor states this is fixed in 1787242135 (unaffected)
Vendor states this is fixed in 1787242321 (unaffected)
Vendor states this is fixed in 1787243221 (unaffected)
Vendor states this is fixed in 1787252179 (unaffected)
Vendor states this is fixed in 1787259106 (unaffected)
Vendor states this is fixed in 1787259284 (unaffected)
Vendor states this is fixed in 1787259310 (unaffected)
Vendor states this is fixed in 1787260663 (unaffected)
Vendor states this is fixed in 1787260689 (unaffected)
Vendor states this is fixed in 1787262214 (unaffected)
Vendor states this is fixed in 1787263584 (unaffected)
Vendor states this is fixed in 1787263693 (unaffected)
Vendor states this is fixed in 1788105072 (unaffected)
Vendor states this is fixed in 2 (unaffected)
60%
Vendor states this is fixed in 7 (unaffected)
Vendor states this is fixed in 8 (unaffected)
Vendor states this is fixed in 9 (unaffected)
All versions
Connectivity Link· Red Hatcontainer
60%All versions
60%
Vendor states this is fixed in 0:1.1.4-1.el10em (unaffected)
Vendor states this is fixed in 0:1.1.4-1.el9em (unaffected)
Vendor states this is fixed in 0:1.2.1-1.el10 (unaffected)
Vendor states this is fixed in 0:1.2.1-1.el9 (unaffected)
Vendor states this is fixed in 0:0.152.1-1.el10_0 (unaffected)
Vendor states this is fixed in 0:0.152.1-1.el10_2 (unaffected)
Vendor states this is fixed in 0:0.152.1-1.el9_4 (unaffected)
Vendor states this is fixed in 0:0.152.1-1.el9_6 (unaffected)
Vendor states this is fixed in 0:0.152.1-1.el9_8 (unaffected)
Vendor states this is fixed in 0:0.2.10-1.el10_2 (unaffected)
Vendor states this is fixed in 0:0.2.3-6.el10_0 (unaffected)
Vendor states this is fixed in 0:0.4.7-5.el10_0 (unaffected)
Vendor states this is fixed in 0:0.4.9.2-1.el10_2 (unaffected)
Vendor states this is fixed in 0:0.9.27-7.el10_2.2 (unaffected)
Vendor states this is fixed in 0:1.0.0-4.el10_2.5 (unaffected)
Vendor states this is fixed in 0:1.0.1-2.el10_2.3 (unaffected)
Vendor states this is fixed in 0:1.26.1-1.el10_0 (unaffected)
Vendor states this is fixed in 0:1.26.4-1.el10_2 (unaffected)
Vendor states this is fixed in 0:1.26.4-1.el9_8 (unaffected)
Vendor states this is fixed in 0:1.26.5-1.el10_0 (unaffected)
Vendor states this is fixed in 0:1.26.5-1.el9_2 (unaffected)
Vendor states this is fixed in 0:1.26.5-1.el9_4 (unaffected)
Vendor states this is fixed in 0:1.26.5-1.el9_6 (unaffected)
Vendor states this is fixed in 0:1.4.0-8.el7_9 (unaffected)
Vendor states this is fixed in 10 (unaffected)
Vendor states this is fixed in 1:0.2.2-1.el9_2.4 (unaffected)
Vendor states this is fixed in 1:0.2.4-9.el9_4 (unaffected)
Vendor states this is fixed in 1:0.2.5-9.el8_10 (unaffected)
Vendor states this is fixed in 1:0.2.7-1.el9_6.5 (unaffected)
Vendor states this is fixed in 1:0.2.7-8.el9_8 (unaffected)
Vendor states this is fixed in 1:0.3.2-5.el10_0 (unaffected)
Vendor states this is fixed in 1:0.3.8-6.el10_2 (unaffected)
Vendor states this is fixed in 2:1.22.2-7.el9_8 (unaffected)
Vendor states this is fixed in 7 (unaffected)
Vendor states this is fixed in 8100020260710105056.a3795dee (unaffected)
Remediation
No guide yetNo remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.
References (100)
Source: cverecord
https://go.dev/cl/783621Source: cverecord
https://go.dev/issue/79694Source: cverecord
https://groups.google.com/g/golang-announce/c/tKs3rmcBcKwSource: cverecord
https://pkg.go.dev/vuln/GO-2026-5037Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://access.redhat.com/errata/RHSA-2026:33574Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://access.redhat.com/security/cve/CVE-2026-27145Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://bugzilla.redhat.com/show_bug.cgi?id=2484207Source: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27145.jsonSSVC — Action Prioritization
SSVCNo known exploitNot automatablePartial impact
SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.
CVSS
6.5MEDIUMCISA-ADP
- Attack Vector
- NETWORK
- Complexity
- HIGH
- Privileges
- NONE
- User Interaction
- NONE
- Scope
- UNCHANGED
- Confidentiality
- NONE
- Integrity
- LOW
- Availability
- HIGH
Vector?
Quick Info
StatusAWAITING ANALYSIS
CWE
CWE-606
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