What’s Vulnerable › Vulnerabilities

CVE-2026-32280: Unexpected work during chain building in crypto/x509

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-08 · updated 2026-09-18
• Weakness: CWE-770

Description

During chain building, the amount of work that is done is not correctly limited when a large number of intermediate certificates are passed in VerifyOptions.Intermediates, which can lead to a denial of service. This affects both direct users of crypto/x509 and users of crypto/tls.

Affected products

• Go: before 1.25.9; from 1.26.0 before 1.26.2 — fixed in 1.25.9, 1.26.2
• Go Stdlib: before 1.25.9; from 1.26.0-0 before 1.26.2 — fixed in 1.25.9, 1.26.2

How to fix

Upgrade to a fixed version: Go 1.25.9, 1.26.2; Go Stdlib 1.25.9, 1.26.2. Check the vendor advisory for mitigations.

References

• https://go.dev/cl/758320
• https://go.dev/issue/78282
• https://groups.google.com/g/golang-announce/c/0uYbvbPZRWU
• https://pkg.go.dev/vuln/GO-2026-4947
• https://access.redhat.com/errata/RHSA-2026:10217
• https://access.redhat.com/errata/RHSA-2026:10219
• https://access.redhat.com/errata/RHSA-2026:10704
• https://access.redhat.com/errata/RHSA-2026:11507
• https://access.redhat.com/errata/RHSA-2026:11514
• https://access.redhat.com/errata/RHSA-2026:11688
• https://access.redhat.com/errata/RHSA-2026:13545
• https://access.redhat.com/errata/RHSA-2026:13791

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