# CVE-2026-111125: CFITSIO heap-based out-of-bounds read in HCOMPRESS decoder

Source: https://junglewise.ai/threats/cve-2026-111125-cfitsio-through-4-7-0-contains-a-heap-based-out-of-bounds-read  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-15. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-111125 · Severity: medium · CVSS 6.1 · Published 2026-10-15

CFITSIO is a C and Fortran library used to read and write FITS astronomical data files. A heap-based out-of-bounds read vulnerability in the HCOMPRESS tile decoder allows attackers to crash applications or disclose heap memory contents by supplying a crafted FITS file. This could affect any application using CFITSIO to process untrusted FITS files.

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

## Quick answers

**Is CVE-2026-111125 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-111125 being exploited in the wild.

**How severe is CVE-2026-111125?** Medium severity, with a CVSS score of 6.1, published 15 October 2026.

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

**Is there a fix for CVE-2026-111125?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-111125 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-111125?** 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.

## Technical details

A heap-based out-of-bounds read exists in the HCOMPRESS tile decoder via the input_nnybble function in fits_hdecompress.c. An attacker can supply a crafted FITS file with ZCMPTYPE HCOMPRESS_1 that declares oversized tile geometry to trigger the vulnerability when applications call fits_read_pix, causing a crash (denial of service) or limited heap memory disclosure.

## Affected products

- HEASARC CFITSIO through 4.7.0

## Timeline

- 2026-10-15: disclosed

## References

- [https://github.com/](https://github.com/)
- [https://github.com/HEASARC/cfitsio](https://github.com/HEASARC/cfitsio)

## Related threats

- [CFITSIO heap out-of-bounds write in ffgcls2](https://junglewise.ai/threats/cve-2026-115504-cfitsio-through-4-7-0-contains-an-out-of-bounds-write)
- [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)