# CVE-2026-116463: FastStone Image Viewer Box-Average Downsampler FUN_0062d96c out-of-bounds

Status: published. Published: 2026-10-26. Updated: 2026-11-02.

A vulnerability was identified in FastStone Image Viewer up to 8.5. Affected is the function FUN_0062d96c of the component Box-Average Downsampler Engine. The manipulation leads to out-of-bounds read. It is possible to initiate the attack remotely. The vendor was contacted early about this disclosure but did not respond in any way.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- FastStone / Image Viewer: 8.0 (affected); 8.1 (affected); 8.2 (affected); 8.3 (affected); 8.4 (affected); 8.5 (affected). Source: CNA: VulDB

## Severity and prioritization

- CVSS 4.0: 5.3 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X; source: CNA: VulDB

- CVSS 3.1: 6.3 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L/E:X/RL:X/RC:R; source: CNA: VulDB

- CVSS 3.0: 6.3 (medium); CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L/E:X/RL:X/RC:R; source: CNA: VulDB

- CVSS 2.0: 7.5 (high); AV:N/AC:L/Au:N/C:P/I:P/A:P/E:ND/RL:ND/RC:UR; source: CNA: VulDB

- CISA KEV: No listing in collected sources

- EPSS: 0.23% as of 2026-11-02; percentile 14.02%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-125, CWE-119

## Exploit evidence

- exploit: https://vuldb.com/submit/1013651 (ADP: CISA-ADP)

## References

- https://vuldb.com/vuln/426360 (CNA: VulDB; vdb-entry, technical-description)

- https://vuldb.com/vuln/426360/cti (CNA: VulDB; signature, permissions-required)

- https://vuldb.com/cve/CVE-2026-116463 (CNA: VulDB; third-party-advisory)

- https://vuldb.com/submit/1013651 (CNA: VulDB; third-party-advisory)

- https://vuldb.com/submit/1013651 (ADP: CISA-ADP; exploit)

## Provenance

- CNA: VulDB: https://www.cve.org/CVERecord?id=CVE-2026-116463; retrieved 2026-11-02; source updated 2026-11-02

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-116463; retrieved 2026-11-02; source updated Not reported

Revision: 5184ac40fe0d4ff3a8500ac30d165c7b596953042eb4f8b1af2fb056a5a31dd6

Canonical: https://y2.dev/cve/CVE-2026-116463

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.