CVE-2026-27145: Inefficient candidate hostname parsing in crypto/x509
Noroxi assessment
Priority: Monitor (action score 26/100)
- Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.59% (FIRST EPSS).
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
- Fixed version: Go standard library crypto/x509 1.25.11, 1.26.4.
Low priority for now. Upgrade to Go standard library crypto/x509 1.25.11, 1.26.4 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
(*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.
- BDU:2026-09275
- ALSA-2026:29980
- ALSA-2026:29981
- ALSA-2026:34357
- ALSA-2026:34359
- ALSA-2026:35832
- ALSA-2026:36317
- ALSA-2026:38995
- ALSA-2026:39573
- ALSA-2026:46394
- ALSA-2026:46395
- GO-2026-5037
- openSUSE-SU-2026:10959-1
- openSUSE-SU-2026:10960-1
- openSUSE-SU-2026:10975-1
- openSUSE-SU-2026:20976-1
- openSUSE-SU-2026:20977-1
- openSUSE-SU-2026:21254-1
- openSUSE-SU-2026:21319-1
- openSUSE-SU-2026:21436-1
- Published
- Jun 2, 2026
- Updated
- Sep 18, 2026
- EPSS
- 0.5% · 48th percentile
- CWE
- CWE-606
Report tools
Action score
26
Monitor
Low priority for now.
- CVSS
- 26 / 40 · 6.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.5%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- Proof of concept exists, no weaponized module
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
Running WordPress? Scan your site free with WP Lens
Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| ansible automation platform | 2.5 | cpe:2.3:redhat:ansible_automation_platform:2.5 |
| ansible automation platform | 2.6 | cpe:2.3:redhat:ansible_automation_platform:2.6 |
| ansible automation platform | 2.7 | cpe:2.3:redhat:ansible_automation_platform:2.7 |
| enterprise linux | 10.2 | cpe:2.3:redhat:enterprise_linux:10.2 |
| enterprise linux eus | 10.0 | cpe:2.3:redhat:enterprise_linux_eus:10.0 |
| rhel els | 7 | cpe:2.3:redhat:rhel_els:7 |
| enterprise linux | 8 | cpe:2.3:redhat:enterprise_linux:8 |
| enterprise linux | 9 | cpe:2.3:redhat:enterprise_linux:9 |
| rhel e4s | 9.2 | cpe:2.3:redhat:rhel_e4s:9.2 |
| rhel e4s | 9.4 | cpe:2.3:redhat:rhel_e4s:9.4 |
| rhel eus | 9.6 | cpe:2.3:redhat:rhel_eus:9.6 |
| openshift | 4.18 | cpe:2.3:redhat:openshift:4.18 |
and 38 more
Versions reported by the vendor
Affected version ranges reported by the assigning authority (Go). Independent of NVD's CPE analysis and usually ahead of it.
Go standard library crypto/x509
- before 1.25.11affected · semver
- 1.26.0-0 and later · before 1.26.4affected · semver
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:10 | go-fdo-client | before 1.0.0-4.el10_2.5 | 1.0.0-4.el10_2.5 |
| AlmaLinux:10 | go-fdo-server | before 1.0.1-2.el10_2.3 | 1.0.1-2.el10_2.3 |
| AlmaLinux:10 | go-fdo-server-manufacturer | before 1.0.1-2.el10_2.3 | 1.0.1-2.el10_2.3 |
| AlmaLinux:10 | go-fdo-server-owner | before 1.0.1-2.el10_2.3 | 1.0.1-2.el10_2.3 |
| AlmaLinux:10 | go-fdo-server-rendezvous | before 1.0.1-2.el10_2.3 | 1.0.1-2.el10_2.3 |
| AlmaLinux:10 | go-toolset | before 1.26.4-1.el10_2.alma.1 | 1.26.4-1.el10_2.alma.1 |
| AlmaLinux:10 | golang | before 1.26.4-1.el10_2.alma.1 | 1.26.4-1.el10_2.alma.1 |
| AlmaLinux:10 | golang-bin | before 1.26.4-1.el10_2.alma.1 | 1.26.4-1.el10_2.alma.1 |
| AlmaLinux:10 | golang-docs | before 1.26.4-1.el10_2.alma.1 | 1.26.4-1.el10_2.alma.1 |
| AlmaLinux:10 | golang-misc | before 1.26.4-1.el10_2.alma.1 | 1.26.4-1.el10_2.alma.1 |
| AlmaLinux:10 | golang-race | before 1.26.4-1.el10_2.alma.1 | 1.26.4-1.el10_2.alma.1 |
| AlmaLinux:10 | golang-src | before 1.26.4-1.el10_2.alma.1 | 1.26.4-1.el10_2.alma.1 |
| AlmaLinux:10 | golang-tests | before 1.26.4-1.el10_2.alma.1 | 1.26.4-1.el10_2.alma.1 |
| AlmaLinux:10 | ipp-usb | before 0.9.27-7.el10_2.2 | 0.9.27-7.el10_2.2 |
| AlmaLinux:10 | opentelemetry-collector | before 0.152.1-1.el10_2 | 0.152.1-1.el10_2 |
| AlmaLinux:10 | yggdrasil | before 0.4.9.2-1.el10_2 | 0.4.9.2-1.el10_2 |
| AlmaLinux:10 | yggdrasil-devel | before 0.4.9.2-1.el10_2 | 0.4.9.2-1.el10_2 |
| AlmaLinux:8 | delve | before 1.26.1-1.module_el8.10.0+4223+bd807c2e | 1.26.1-1.module_el8.10.0+4223+bd807c2e |
| AlmaLinux:8 | go-toolset | before 1.26.5-1.module_el8.10.0+4223+bd807c2e | 1.26.5-1.module_el8.10.0+4223+bd807c2e |
| AlmaLinux:8 | golang | before 1.26.5-1.module_el8.10.0+4223+bd807c2e | 1.26.5-1.module_el8.10.0+4223+bd807c2e |
| AlmaLinux:8 | golang-bin | before 1.26.5-1.module_el8.10.0+4223+bd807c2e | 1.26.5-1.module_el8.10.0+4223+bd807c2e |
| AlmaLinux:8 | golang-docs | before 1.26.5-1.module_el8.10.0+4223+bd807c2e | 1.26.5-1.module_el8.10.0+4223+bd807c2e |
| AlmaLinux:8 | golang-misc | before 1.26.5-1.module_el8.10.0+4223+bd807c2e | 1.26.5-1.module_el8.10.0+4223+bd807c2e |
| AlmaLinux:8 | golang-race | before 1.26.5-1.module_el8.10.0+4223+bd807c2e | 1.26.5-1.module_el8.10.0+4223+bd807c2e |
+96
Same product
go standard library: all recordsOther highest-scoring records for the same primary product.
- CVE-2025-22874Usage of ExtKeyUsageAny disables policy validation in crypto/x50930Monitor
- CVE-2025-22865ParsePKCS1PrivateKey panic with partial keys in crypto/x50930Monitor
- CVE-2026-111943Distrust compromised intermediate certificates in crypto/x50927Monitor
Published before and after this one in the same product
- ← EarlierCVE-2024-24783Mar 5, 2024 · Verify panics on certificates with an unknown public key algorithm in crypto/x50923Monitor
- ← EarlierCVE-2024-45341Jan 27, 2025 · Usage of IPv6 zone IDs can bypass URI name constraints in crypto/x50924Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Go standard library crypto/x509 | 1.25.11 | Vendor (CNA) |
| Go standard library crypto/x509 | 1.26.4 | Vendor (CNA) |
| azl3 golang 1.27.0-1 on Azure Linux 3.0 | — | Microsoft (MSRC) |
| almalinux:delve | 1.26.1-1.module_el8.10.0+4223+bd807c2e · AlmaLinux:8 | Package registry (OSV) |
| almalinux:go-toolset | 1.26.4-1.el10_2.alma.1 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:go-toolset | 1.26.5-1.module_el8.10.0+4223+bd807c2e · AlmaLinux:8 | Package registry (OSV) |
| almalinux:golang | 1.26.4-1.el10_2.alma.1 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:golang | 1.26.5-1.module_el8.10.0+4223+bd807c2e · AlmaLinux:8 | Package registry (OSV) |
| almalinux:golang-bin | 1.26.4-1.el10_2.alma.1 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:golang-bin | 1.26.5-1.module_el8.10.0+4223+bd807c2e · AlmaLinux:8 | Package registry (OSV) |
| almalinux:golang-docs | 1.26.4-1.el10_2.alma.1 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:golang-docs | 1.26.5-1.module_el8.10.0+4223+bd807c2e · AlmaLinux:8 | Package registry (OSV) |
| almalinux:golang-misc | 1.26.4-1.el10_2.alma.1 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:golang-misc | 1.26.5-1.module_el8.10.0+4223+bd807c2e · AlmaLinux:8 | Package registry (OSV) |
| almalinux:golang-race | 1.26.4-1.el10_2.alma.1 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:golang-race | 1.26.5-1.module_el8.10.0+4223+bd807c2e · AlmaLinux:8 | Package registry (OSV) |
| almalinux:golang-src | 1.26.4-1.el10_2.alma.1 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:golang-src | 1.26.5-1.module_el8.10.0+4223+bd807c2e · AlmaLinux:8 | Package registry (OSV) |
| almalinux:golang-tests | 1.26.4-1.el10_2.alma.1 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:ipp-usb | 0.9.27-7.el10_2.2 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:opentelemetry-collector | 0.152.1-1.el10_2 · AlmaLinux:10 | Package registry (OSV) |
| almalinux:skopeo | 2:1.22.2-7.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:skopeo-tests | 2:1.22.2-7.el9_8 · AlmaLinux:9 | Package registry (OSV) |
| debian:golang-1.25 | 1.25.11-1 · Debian:14 | Package registry (OSV) |
| debian:golang-1.26 | 1.26.4-1 · Debian:14 | Package registry (OSV) |
| Go:stdlib | 1.25.11 | Package registry (OSV) |
| Go:stdlib | 1.26.4 | Package registry (OSV) |
| opensuse:go1.25 | 1.25.11-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:go1.25-openssl | 1.25.12-160000.1.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:go1.26 | 1.26.4-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
+34
Exploit status
Proof of concept available
A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.
Evidence
- Proof-of-concept repository on GitHub ×1
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Proof-of-concept repository on GitHub | stars:0 | 2026-06-03 |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- Published
- First PoCsame day
- TodayNov 4, 2026+154 d
No history yet (it accumulates with the daily EPSS job).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- none
- Integrity
- low · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- Low
- Availability impact
- High
Weakness class (CWE)
CWE-606 · Unchecked Input for Loop ConditionCVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (19 more)Show less
- access.redhat.com/errata/RHSA-2026:50205
- go.dev/cl/783621
- go.dev/issue/79694
- groups.google.com/g/golang-announce/c/tKs3rmcBcKw
- pkg.go.dev/vuln/GO-2026-5037
- access.redhat.com/errata/RHSA-2026:23262
- access.redhat.com/errata/RHSA-2026:23264
- access.redhat.com/errata/RHSA-2026:29980
- access.redhat.com/errata/RHSA-2026:29981
- access.redhat.com/errata/RHSA-2026:33574
- access.redhat.com/errata/RHSA-2026:34357
- access.redhat.com/errata/RHSA-2026:34359
- access.redhat.com/errata/RHSA-2026:35832
- access.redhat.com/errata/RHSA-2026:36317
- access.redhat.com/errata/RHSA-2026:36648
- access.redhat.com/errata/RHSA-2026:36797
- access.redhat.com/errata/RHSA-2026:38995
- access.redhat.com/errata/RHSA-2026:39005
- access.redhat.com/errata/RHSA-2026:39573
Vendor advisories and official records. Exploit/PoC links are deliberately left out.