CVE-2025-61727 Improper application of excluded DNS name constraints when verifying wildcard names in crypto/x509
Attackers can bypass DNS name constraints in certificate chains by using wildcard SANs, potentially enabling man-in-the-middle attacks.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-61727?
CVE-2025-61727 is a medium-severity vulnerability in Golang Go, published on 3 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
An excluded subdomain constraint in a certificate chain does not restrict the usage of wildcard SANs in the leaf certificate. For example a constraint that excludes the subdomain test.example.com does not prevent a leaf certificate from claiming the SAN *.example.com.
Weakness: CWE-295
Which versions are affected by CVE-2025-61727?
2 open source packages ship an affected version, including golang and stdlib. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
golang Bitnami | All versions | 1.24.11, 1.25.5 |
stdlib Go | All versions | 1.24.11, 1.25.5 |
Linux distribution packages (8)
golang-fips1.25 Red Hat:hummingbird:1 | All versions | 0:1.25.8-0.1.hum1 |
golang-fips1.25-bin Red Hat:hummingbird:1 | All versions | 0:1.25.8-0.1.hum1 |
golang-fips1.25-docs Red Hat:hummingbird:1 | All versions | 0:1.25.8-0.1.hum1 |
golang-fips1.25-misc Red Hat:hummingbird:1 | All versions | 0:1.25.8-0.1.hum1 |
golang-fips1.25-race Red Hat:hummingbird:1 | All versions | 0:1.25.8-0.1.hum1 |
golang-fips1.25-src Red Hat:hummingbird:1 | All versions | 0:1.25.8-0.1.hum1 |
golang-fips1.25-tests Red Hat:hummingbird:1 | All versions | 0:1.25.8-0.1.hum1 |
kubelogin openSUSE:Tumbleweed | All versions | 0.2.14-1.1 |
Products include Golang Go.
How do I fix CVE-2025-61727?
Upgrade golang to a fixed version for your release line: 1.24.11 or 1.25.5.
Is CVE-2025-61727 being exploited?
There is no known exploitation of CVE-2025-61727 in the wild and no public exploit code.
Other vulnerabilities in Golang Go
- CVE-2020-0601 Microsoft Windows CryptoAPI Spoofing
- CVE-2026-27143 Missing bound checks can lead to memory corruption in safe Go in cmd/compile
- CVE-2024-24790 Unexpected behavior from Is methods for IPv4-mapped IPv6 addresses in net/netip
- CVE-2023-39320 Arbitrary code execution via go.mod toolchain directive in cmd/go
- CVE-2023-24540 Improper handling of JavaScript whitespace in html/template
Sources
Also known as AZL-71447, AZL-71635, AZL-78927, AZL-98646, BELL-CVE-2025-61727, BIT-golang-2025-61727 and 363 more.