# CVE-2026-90556 — freeciv

> As of 2026-09-12, CVE-2026-90556 is a HIGH-severity vulnerability in freeciv, CVSS v3.1 7.8. No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-90556 as of 2026-09-12; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-09-12

## What is CVE-2026-90556?

Freeciv versions before 3.2.6 contain a heap buffer overflow in worklist_load() when processing savegame files with declared worklist lengths exceeding the fixed array bound of 64 elements. Attackers can craft malicious savegame files that write past the entries array into adjacent heap-allocated struct fields, potentially corrupting memory when a user or server operator loads the file.

The record classifies CVE-2026-90556 under weakness class [CWE-122](https://intel.threadlinqs.com/cwe/CWE-122). Its CVSS v3 base vector states that the flaw requires local access to the host, needs no prior authentication, needs a user to take an action first, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 23 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 7.8 — HIGH (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **CVSS v4.0 base score:** 8.5 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 3.9/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-09-12

## Is CVE-2026-90556 being exploited?

It currently carries a trending score of 30 in the Threadlinqs vulnerability feed.

## Affected products and versions

- **freeciv**: freeciv

## How to fix CVE-2026-90556

No vendor patch reference has been recorded for CVE-2026-90556 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-90556

No threat campaign in the Threadlinqs corpus currently references CVE-2026-90556, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, NVD. Last verified by Threadlinqs on 2026-09-14. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [github.com — patch](https://github.com/freeciv/freeciv/commit/75ecde3e86ddf2fe775768450e9a290a4f4d4387)
- [github.com — release notes](https://github.com/freeciv/freeciv/releases/tag/R3_2_6)

**Technical analysis**

- [github.com — technical description](https://github.com/freeciv/freeciv/blob/R3_2_5/server/savegame/savegame3.c#L964)
- [github.com — technical description (savegame2)](https://github.com/freeciv/freeciv/blob/R3_2_5/server/savegame/savegame2.c#L788)

**Third-party advisory**

- [vulncheck.com — third party advisory](https://www.vulncheck.com/advisories/freeciv-before-3.2.6-heap-buffer-overflow-via-worklist-load)

**Issue tracking and product pages**

- [github.com — product](https://github.com/freeciv/freeciv)
- [redmine.freeciv.org — issue tracking](https://redmine.freeciv.org/issues/2161)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-90556
Full detection coverage and IOCs for threats exploiting CVE-2026-90556 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp