CVE-2025-66506— Fulcio allocates excessive memory during token parsing
Quick assessment
Affected
sigstore fulcio
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
Fulcio是sigstore开源的一个证书颁发机构。 Fulcio 1.8.3之前版本存在安全漏洞，该漏洞源于identity.extractIssuerURL函数处理不当，可能导致内存分配问题。
Possible ATT&CK Techniques 1 AI
T1496 · Resource Hijacking
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I. Basic Information for CVE-2025-66506
Vulnerability Information
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Vulnerability Title
Fulcio allocates excessive memory during token parsing
Source: CVE Program / CVE List V5
Vulnerability Description
Fulcio is a free-to-use certificate authority for issuing code signing certificates for an OpenID Connect (OIDC) identity. Prior to 1.8.3, function identity.extractIssuerURL splits (via a call to strings.Split) its argument (which is untrusted data) on periods. As a result, in the face of a malicious request with an (invalid) OIDC identity token in the payload containing many period characters, a call to extractIssuerURL incurs allocations to the tune of O(n) bytes (where n stands for the length of the function's argument), with a constant factor of about 16. This vulnerability is fixed in 1.8.3.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
不对称的资源消耗(放大攻击)
Source: CVE Program / CVE List V5
Vulnerability Title
Fulcio 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Fulcio是sigstore开源的一个证书颁发机构。 Fulcio 1.8.3之前版本存在安全漏洞，该漏洞源于identity.extractIssuerURL函数处理不当，可能导致内存分配问题。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2025-66506
| # | POC Description | Source Link | Shenlong Link |
|---|
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Qwen3.6-35B-A3B
· 7998 chars
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III. Intelligence Information for CVE-2025-66506
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V. Comments for CVE-2025-66506
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