CVE-2025-23016

CRITICALNVD 9.39.3—
EchelonGraph scoreMEDIUM confidence

Score 9.3 from GitHub Security Advisory (severity: CRITICAL) published 2025-01-10. NVD baseline CVSS 9.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this weekElevated
9.3EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.3Exploit: Elevated riskExposed: 0

A fix is available — apply it.

FastCGI fcgi2 (aka fcgi) 2.x through 2.4.4 has an integer overflow (and resultant heap-based buffer overflow) via crafted nameLen or valueLen values in data to the IPC socket. This occurs in ReadParams in fcgiapp.c.

CVSS v3
9.3
EG Score
9.3(medium)
EG Risk
58(Track*)
EG Risk 58/100SSVC: Track*

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity93% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
1%
EPSS %ILE
44%
KEV
Not listed

Published

January 10, 2025

Last Modified

April 15, 2026

Advisory Details (5)

Auto-updated May 21, 2026
🔬 Proof of concept available. Patch available.
generic

CVE-2025-23016 - Exploiting the FastCGI library

https://www.synacktiv.com/en/publications/cve-2025-23016-exploiting-the-fastcgi-library
generic Patch Available

[SECURITY] [DLA 4329-1] libfcgi security update

https://lists.debian.org/debian-lts-announce/2025/10/msg00009.html
generic

oss-security - CVE-2025-23016: Integer & buffer overflow in fastcgi < 2.4.5

http://www.openwall.com/lists/oss-security/2025/04/23/4
generic

Release fix CVE-2025-23016 · FastCGI-Archives/fcgi2 · GitHub

https://github.com/FastCGI-Archives/fcgi2/releases/tag/2.4.5
generic🟡 PoC Available

[Security vulnerability - memory corruption] Integer overflow into heap overflow · Issue #67 · FastCGI-Archives/fcgi2 · GitHub

https://github.com/FastCGI-Archives/fcgi2/issues/67

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibfcgi0t64 (2.4.2-2.1ubuntu0.25.04.1) @ plucky2026-05-21ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(2)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 10× in last 7d / 42× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 131 total refreshes for this CVE.

  1. 2026-07-28 15:35 UTCEPSS rescore
  2. 2026-07-28 04:24 UTCOSV refresh
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Frequently asked(5)

What is CVE-2025-23016?
CVE-2025-23016 is a critical vulnerability published on January 10, 2025. FastCGI fcgi2 (aka fcgi) 2.x through 2.4.4 has an integer overflow (and resultant heap-based buffer overflow) via crafted nameLen or valueLen values in data to the IPC socket. This occurs in ReadParams in fcgiapp.c.
When was CVE-2025-23016 disclosed?
CVE-2025-23016 was first published in the National Vulnerability Database on January 10, 2025, with the most recent update on April 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-23016 actively exploited?
CVE-2025-23016 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 56.3% of all scored CVEs.
What is the CVSS score of CVE-2025-23016?
CVE-2025-23016 has a CVSS v3 base score of 9.3 (NVD).
How do I remediate CVE-2025-23016?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-23016, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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