GHSA-pr85-w493-9w3x: resdata (CVE-2026-55209)

resdata has Classic Buffer Overflow, Improper Validation of Array Index, NULL Pointer Dereference and Out-of-bounds Read

CVSS 9.8 CriticalCriticalEPSS 0.0078 · 56th percentile

Critical, because:

CVSS score 9.8: 9.0 or more.

How we decide what’s critical

Published by the GitHub Advisory Database at 18 Aug 2026, 20:11 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

Package	Ecosystem	Affected	Fixed in
resdata	PyPI	<6.2.9	6.2.9

Identifiers

GHSA-pr85-w493-9w3x · CVE-2026-55209 · PYSEC-2026-3694

Weakness (CWE)

CWE-120 · CWE-125 · CWE-129 · CWE-476

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

resdata versions before 6.2.9 do not correctly validate input in GRDECL files, which can lead to buffer overflow, array index, NULL pointer and out-of-bounds read problems. An attacker who can supply a crafted GRDECL file to resdata, for example through a web service that parses untrusted files, may be able to affect the program. Upgrade resdata to version 6.2.9 or later.

Written 5 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
9.8	Critical	3.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.0078, the 56th percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 14:39 UTC First seen by agentprime
31 Oct 2026, 14:39 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.