# CVE-2026-115504: CFITSIO heap out-of-bounds write in ffgcls2

Source: https://junglewise.ai/threats/cve-2026-115504-cfitsio-through-4-7-0-contains-an-out-of-bounds-write  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-22. Updated: 2026-10-22  
License: CC BY 4.0 with a link back

CVE-2026-115504 · Severity: high · CVSS 7.8 · Published 2026-10-22

CFITSIO is a library for reading and writing FITS astronomical data files. A crafted FITS file can trigger a heap buffer overflow in the variable-length string column handler, allowing an attacker to corrupt memory and execute arbitrary code when the file is processed by applications using CFITSIO, such as fitsverify.

Technologies: [HEASARC CFITSIO](https://junglewise.ai/threats/technologies/cfitsio). Vendors: [HEASARC](https://junglewise.ai/threats/vendors/heasarc).

## Quick answers

**Is CVE-2026-115504 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-115504 being exploited in the wild.

**How severe is CVE-2026-115504?** High severity, with a CVSS score of 7.8, published 22 October 2026.

**Which products and versions are affected?** HEASARC CFITSIO through 4.7.0.

**Is there a fix for CVE-2026-115504?** Yes: fixed in CFITSIO versions including commit de7da7908bca0b9ed70d219a35e8627667ced779 or later (merged in PR #184, 2026-09-14). Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-115504 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-115504?** Check whether you run HEASARC CFITSIO 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.

## How to fix

- Fixed in CFITSIO versions including commit de7da7908bca0b9ed70d219a35e8627667ced779 or later (merged in PR #184, 2026-09-14)

## Technical details

An out-of-bounds write vulnerability exists in ffgcls2() (getcols.c) where attacker-controlled column width values from FITS file headers are used to write into a fixed-size heap buffer without bounds validation. This allows heap memory corruption leading to arbitrary code execution. The fix adds bounds checking before the write operation.

## Affected products

- HEASARC CFITSIO through 4.7.0

## Timeline

- 2026-10-22: disclosed
- 2026-09-14: patched: Public fix merged to develop branch

## References

- [https://github.com/](https://github.com/)
- [https://gist.github.com/yure1432/98f15c7e8f48dc90ae65646f926aa176](https://gist.github.com/yure1432/98f15c7e8f48dc90ae65646f926aa176)

## Related threats

- [CFITSIO heap-based out-of-bounds read in HCOMPRESS decoder](https://junglewise.ai/threats/cve-2026-111125-cfitsio-through-4-7-0-contains-a-heap-based-out-of-bounds-read)
- [CFITSIO heap-based out-of-bounds read in imcompress](https://junglewise.ai/threats/cve-2026-111124-cfitsio-through-4-7-0-contains-a-heap-based-out-of-bounds-read)