CVE-2026-32281
Denial of Service via Inefficient Policy Mapping in Go Cert Validation
Publication date: 2026-04-08
Last updated on: 2026-04-16
Assigner: Go Project
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| golang | go | to 1.25.9 (exc) |
| golang | go | From 1.26.0 (inc) to 1.26.2 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-295 | The product does not validate, or incorrectly validates, a certificate. |
Attack-Flow Graph
AI Powered Q&A
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
The provided information does not specify any direct impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.
Can you explain this vulnerability to me?
CVE-2026-32281 is a vulnerability in the Go programming language's crypto/x509 package related to certificate policy validation during X.509 certificate verification.
When validating certificate chains that contain certificates with a very large number of policy mappings, the verification process becomes unexpectedly inefficient. Specifically, if policy mapping is inhibited by an earlier certificate in the chain, the code repeatedly rescans the entire policy graph for each policy mapping entry, causing verification time to grow approximately quadratically with the number of policy mappings.
This inefficiency can cause significant performance degradation, turning a normally quick verification process into one that takes several seconds, especially with large certificate data.
The vulnerability affects only the validation of otherwise trusted certificate chains issued by a root CA in the configured root certificate pool.
How can this vulnerability impact me? :
This vulnerability can cause a denial of service (DoS) condition by making the certificate verification process extremely slow when processing certificate chains with many policy mappings.
Applications that verify peer-supplied certificate chains against a configured root pool, such as mutual TLS (mTLS) implementations, private PKI services, or APIs accepting certificate chains as input, are primarily affected.
The performance degradation can lead to resource exhaustion or unresponsiveness in these applications, potentially disrupting normal operations.
How can this vulnerability be detected on my network or system? Can you suggest some commands?
This vulnerability manifests as a significant performance degradation during the verification of X.509 certificate chains that contain a very large number of policy mappings. Detection involves observing unusually long verification times when processing certificate chains, especially those validated against trusted root CAs.
To detect this on your system, you can monitor the performance of applications that perform certificate verification using Go's crypto/x509 package, particularly those that handle peer-supplied certificate chains such as mutual TLS (mTLS) services or private PKI systems.
While no specific commands are provided in the resources, a practical approach is to instrument or log the duration of certificate verification calls in your Go applications, for example by timing calls to the `x509.Certificate.Verify` function.
Additionally, you can analyze certificate chains to identify if they contain certificates with large `PolicyMappings` extensions, which trigger the inefficiency. Tools like OpenSSL can be used to inspect certificate extensions, for example:
- openssl x509 -in certificate.pem -text -noout
Look for the Policy Mappings extension in the output to identify certificates with many policy mappings.
What immediate steps should I take to mitigate this vulnerability?
Immediate mitigation steps include avoiding the use of Go versions affected by this vulnerability, specifically versions before 1.25.9 and from 1.26.0 up to but not including 1.26.2.
If upgrading is not immediately possible, consider limiting or validating the certificate chains your application accepts to avoid those containing certificates with large PolicyMappings extensions.
Additionally, monitor and restrict inputs to your certificate verification processes to reduce exposure to potentially malicious or malformed certificate chains that could trigger the denial of service.
Keep track of updates from the Go project for patches addressing this issue, as the vulnerability is acknowledged and a fix is planned.