# CVE-2026-9501: GNU LibreDWG reachable assertion in decompress_R2004_section

Source: https://junglewise.ai/threats/cve-2026-9501-gnu-libredwg-reachable-assertion-in-decompress-r2004-section  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-25. Updated: 2026-05-26  
License: CC BY 4.0 with a link back

CVE-2026-9501 · Severity: low · CVSS 3.3 · Published 2026-05-25

A vulnerability exists in GNU LibreDWG, a library used for reading and writing CAD files. By providing a specially crafted DWG file, an attacker can cause the software to crash. This impact is limited to a denial-of-service on the local system where the file is processed, potentially disrupting operations or automated workflows that handle CAD data.

Technologies: [Gnu LibreDWG](https://junglewise.ai/threats/technologies/libredwg). Vendors: [Gnu](https://junglewise.ai/threats/vendors/gnu).

## Quick answers

**Is CVE-2026-9501 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-9501 being exploited in the wild.

**How severe is CVE-2026-9501?** Low severity, with a CVSS score of 3.3, published 25 May 2026.

**Which products and versions are affected?** Gnu LibreDWG up to 0.14.

**Is there a fix for CVE-2026-9501?** A patch was published on 2026-05-25: Patch commit e501cb9 identified Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-9501 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-9501?** Check whether you run Gnu LibreDWG at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A reachable assertion vulnerability exists in the decompress_R2004_section function within src/decode.c of GNU LibreDWG (up to version 0.14). The issue is triggered when the Dwgread Utility processes a malformed DWG R2004 file where internal decompression pointers (pos) are manipulated to be smaller than the expected offset (comp_offset). This violation of the assertion constraint `(long)pos >= (long)comp_offset` causes the program to abort. An attacker with local access can exploit this to cause a denial-of-service (crash). A patch (commit e501cb9) has been released to address this by adding proper bounds checking for decompression bytes and offsets.

## Affected products

- GNU LibreDWG up to 0.14

## Timeline

- 2026-04-22: disclosed: Issue reported on GitHub by HackC0der
- 2026-05-25: advisory: NVD publication date
- 2026-05-25: patched: Patch commit e501cb9 identified

## References

- [https://github.com/HackC0der/CVE-Repos/blob/main/libredwg/libredwg_6d6a339_assert_fail_decompress_R2004_section.dwg](https://github.com/HackC0der/CVE-Repos/blob/main/libredwg/libredwg_6d6a339_assert_fail_decompress_R2004_section.dwg)
- [https://github.com/LibreDWG/libredwg/commit/e501cb9926c1e9a07a0d1cc997f3e69e9be801c9](https://github.com/LibreDWG/libredwg/commit/e501cb9926c1e9a07a0d1cc997f3e69e9be801c9)
- [https://github.com/LibreDWG/libredwg/issues/1242](https://github.com/LibreDWG/libredwg/issues/1242)
- [https://vuldb.com/submit/814250](https://vuldb.com/submit/814250)
- [https://vuldb.com/vuln/365483](https://vuldb.com/vuln/365483)
- [https://vuldb.com/vuln/365483/cti](https://vuldb.com/vuln/365483/cti)
- [https://www.gnu.org/](https://www.gnu.org/)

## Related threats

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