CVE-2025-66564: Github.com/sigstore/timestamp authority Sigstore Timestamp Authority Allocates Excessive Vulnerability
HIGHCVE-2025-66564 is a HIGH (CVSS 7.5) sigstore timestamp authority allocates excessive vulnerability (CWE-405: Asymmetric Resource Consumption (Amplification)) affecting Github.com/sigstore/timestamp authority libraries in the Go ecosystem. The issue involves sigstore timestamp authority allocates excessive memory during request parsing. Remediation is available by upgrading affected packages to version 2.0.3.
CVE-2025-66564 at a Glance
Security Impact
CVSS: 7.5
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
How to Fix CVE-2025-66564
To remediate this vulnerability, upgrade all affected Github.com/sigstore/timestamp authority dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
Upgrade github.com/sigstore/timestamp-authority to 2.0.3Run the following command in your project directory to verify that all resolved dependencies use the patched release:
inspect dependencies for github.com/sigstore/timestamp-authorityHow to Check if You Are Affected
To determine whether your application is affected by CVE-2025-66564, inspect your project dependencies for Github.com/sigstore/timestamp authority:
inspect dependencies for github.com/sigstore/timestamp-authorityAnalyze the terminal output to locate any version of Github.com/sigstore/timestamp authority in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.0.3), your application is affected.
Note: Verify declared build manifests and deployed runtime container environments.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-405: Asymmetric Resource Consumption (Amplification), where the product does not properly control situations in which an adversary can cause the product to consume or produce excessive resources without requiring the adversary to invest equivalent work or otherwise prove authorization, i.e., the adversary's influence is "asymmetric.". In Github.com/sigstore/timestamp authority, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2025-66564 Affected Github.com/sigstore/timestamp authority Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
github.com/sigstore/timestamp-authority
|
Go |
< 2.0.3
|
2.0.3
|
References
Frequently Asked Questions
What is CVE-2025-66564?
Which Github.com/sigstore/timestamp authority versions are affected?
What version fixes CVE-2025-66564?
Is github.com/sigstore/timestamp-authority affected?
What is the CVSS score of CVE-2025-66564?
What CWE is associated with CVE-2025-66564?
How can I check Go dependencies for CVE-2025-66564?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-4qg8-fj49-pxjh",
"modified" : "2025-12-05T18:19:00Z",
"published" : "2025-12-05T18:19:00Z",
"aliases" : [ "CVE-2025-66564" ],
"summary" : "Sigstore Timestamp Authority allocates excessive memory during request parsing",
"details" : "### Impact\n\n**Excessive memory allocation**\n\nFunction [api.ParseJSONRequest](https://github.com/sigstore/timestamp-authority/blob/26d7d426d3000abdbdf2df34de56bb92246c0365/pkg/api/timestamp.go#L63) currently splits (via a call to [strings.Split](https://pkg.go.dev/strings#Split)) an optionally-provided OID (which is untrusted data) on periods. Similarly, function [api.getContentType](https://github.com/sigstore/timestamp-authority/blob/26d7d426d3000abdbdf2df34de56bb92246c0365/pkg/api/timestamp.go#L114) splits the `Content-Type` header (which is also untrusted data) on an `application` string.\n\nAs a result, in the face of a malicious request with either an excessively long OID in the payload containing many period characters or a malformed `Content-Type` header, a call to `api.ParseJSONRequest` or `api.getContentType` incurs allocations of O(n) bytes (where n stands for the length of the function's argument). Relevant weakness: [CWE-405: Asymmetric Resource Consumption (Amplification)](https://cwe.mitre.org/data/definitions/405.html)\n\n### Patches\n\nUpgrade to v2.0.3.\n\n### Workarounds\n\nThere are no workarounds with the service itself. If the service is behind a load balancer, configure the load balancer to reject excessively large requests.",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "Go",
"name" : "github.com/sigstore/timestamp-authority"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "2.0.3"
} ]
} ],
"database_specific" : {
"last_known_affected_version_range" : "<= 2.0.2"
}
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/sigstore/timestamp-authority/security/advisories/GHSA-4qg8-fj49-pxjh"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-66564"
}, {
"type" : "WEB",
"url" : "https://github.com/sigstore/timestamp-authority/commit/0cae34e197d685a14904e0bad135b89d13b69421"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/sigstore/timestamp-authority"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-405" ],
"severity" : "HIGH",
"github_reviewed" : true,
"github_reviewed_at" : "2025-12-05T18:19:00Z",
"nvd_published_at" : "2025-12-04T23:15:47Z"
}
}