CVE-2025-66564 | Sigstore Timestamp Authority allocates excessive memory during request parsing

Sigstore Timestamp Authority is a service for issuing RFC 3161 timestamps. Prior to 2.0.3, Function api.ParseJSONRequest currently splits (via a call to strings.Split) an optionally-provided OID (which is untrusted data) on periods. Similarly, function api.getContentType splits the Content-Type header (which is also untrusted data) on an application string. As 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). This vulnerability is fixed in 2.0.3.

Published: 2025-12-04 Last update: 2026-03-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-66564 is rated Low Risk (31.1/100): CVSS High severity, with low exploitation likelihood (EPSS 0.02%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-66564

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-12-18 0.05% 0.02% -0.03%
2 2025-12-10 0.04% 0.05% +0.01%
3 2025-12-05 — 0.04% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-66564

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2025-66564

GitHub Security Advisory for CVE-2025-66564

GHSA-4qg8-fj49-pxjh · Severity: high · Ecosystem: go — Sigstore Timestamp Authority allocates excessive memory during request parsing

OS Trackers for CVE-2025-66564

vendor priority summary link
debian not yet assigned CVE-2025-66564 not yet assigned priority: Debian including 1 source packages (golang-github-sigstore-timestamp-authority), 3 status rows across 3 suites (forky, sid, trixie): resolved 2, open 1. https://security-tracker.debian.org/tracker/CVE-2025-66564
redhat high — https://access.redhat.com/security/cve/CVE-2025-66564
ubuntu medium CVE-2025-66564 medium priority: Ubuntu including 1 source packages (golang-github-sigstore-timestamp-authority), 5 status rows across 5 suites (jammy, noble, plucky, questing, upstream): DNE 2, needs-triage 2, ignored 1. https://ubuntu.com/security/CVE-2025-66564

Affected software / configurations for CVE-2025-66564

Vendor Product Version Raw CPE
linuxfoundation sigstore_timestamp_authority < 2.0.3 cpe:2.3:a:linuxfoundation:sigstore_timestamp_authority:*:*:*:*:*:*:*:*

References for CVE-2025-66564

cvelogic Threat Intelligence