Fulcio allocates excessive memory during token parsing

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-66506
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-12-04 22:15:49 UTC
Updated2026-10-18 15:10:00 UTC
DescriptionFulcio 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-405 | CWE-405 CWE-405: Asymmetric Resource Consumption (Amplification)

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Linuxfoundation Fulcio All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Sigstore Fulcio affected < 1.8.3 Not specified

References

ReferenceSourceLinkTags
github.com/sigstore/fulcio/security/advisories/GHSA-f83f-xpx7-ffpw [email protected] github.com Vendor Advisory
github.com/sigstore/fulcio/commit/765a0e57608b9ef390e1eeeea8595b9054c63a5a [email protected] github.com Patch
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