CVE-2026-90556: Heap Overflow (CVSS 7.8)

Description

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.

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CVSS v3.1 Score

7.8

HIGH

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

EPSS — Exploit Prediction

0.0014

Probability of exploitation

0.04%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-122 CWE-122

References

Other References

https://github.com/freeciv/freeciv https://github.com/freeciv/freeciv/blob/R3_2_5/server/savegame/savegame2.c#L788 https://github.com/freeciv/freeciv/blob/R3_2_5/server/savegame/savegame3.c#L964 https://github.com/freeciv/freeciv/commit/75ecde3e86ddf2fe775768450e9a290a4f4d4387 https://github.com/freeciv/freeciv/releases/tag/R3_2_6 https://redmine.freeciv.org/issues/2161 https://www.vulncheck.com/advisories/freeciv-before-3.2.6-heap-buffer-overflow-via-worklist-load

Frequently Asked Questions

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. It has a CVSS v3.1 base score of 7.8 (HIGH).

How severe is CVE-2026-90556? +

CVE-2026-90556 has a CVSS v3.1 score of 7.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0014, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-90556? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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