ZeroHour

CVE-2026-91752

niche

Stack Overflow DoS in GNU libextractor StarOffice Parser (pre-1.15)

CVSS 4.0
8.7 high
EPSS
Published
()
Modified
AI analysis

GNU libextractor before 1.15 contains a stack-based buffer overflow (CWE-789, memory allocation with an excessive size value) in the process_star_office function, which sizes a variable-length stack array from attacker-controlled OLE2 stream data. An attacker crafts a malicious StarOffice-format document; when any libextractor-based application extracts its metadata, the parser can be driven to allocate up to 4 MB on the stack, overflowing it and crashing the process. The CVSS 4.0 score of 8.7 reflects a network attack vector with no privileges, no user interaction, and availability-only impact (VA:H, VC:N/VI:N), so the demonstrated effect is denial of service rather than code execution. Any product or service that links libextractor before 1.15 and extracts metadata from untrusted documents — for example file-indexing, search, or upload-scanning services — is affected. No public proof of concept is known, the flaw is not on the CISA KEV list, and no exploitation in the wild has been reported.

What to do: Upgrade to GNU libextractor 1.15 or later, and audit whether applications that embed the library (file managers, search indexers, upload-scanning services, GNUnet) link a version before 1.15. If patching is delayed, restrict or sandbox metadata extraction of untrusted StarOffice/legacy OLE2-based documents, for example by running extraction in a separate memory-limited worker process so a crash cannot take down the parent service. Monitor metadata-extraction pipelines for crashes on OLE2/StarOffice documents as a possible indicator of attempted exploitation.

Affected
GNU libextractorbefore 1.15
Estimated exposure
niche≈low tens of thousands of installations at most (order of magnitude) — libextractor is a niche GNU metadata-extraction library packaged in major Linux distributions and consumed mainly by projects like GNUnet and desktop file-indexing tools; no public scan data or active-install counts exist for…

Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.

Description

GNU libextractor before 1.15 contains a stack-based buffer overflow vulnerability in the process_star_office function that sizes a variable-length stack array from attacker-controlled OLE2 stream data. Attackers can craft malicious StarOffice documents that allocate up to 4 MB on the stack, causing stack overflow and crashing any application extracting metadata from the document.

Weakness
CWE-789
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

In the news

GNU security advisory (AV26-923)

Canadian Cyber Centre advisory AV26-923 flags a stack overflow in GNU libextractor before v1.15 via OLE2 files.

The Canadian Centre for Cyber Security issued advisory AV26-923 on September 15, 2026, covering CVE-2026-91752, a stack overflow vulnerability in GNU libextractor versions prior to 1.15 triggered via OLE2 file parsing. The Cyber Centre encourages users and administrators to review the provided links and apply necessary updates as they become available.