CVE-2026-115504: Out-of-bounds Write in HEASARC cfitsio

CVE-2026-115504 is an out-of-bounds write vulnerability in the HEASARC cfitsio library, specifically in the ffgcls2() function within getcols.c. The vulnerability occurs because the function trusts heap descriptor lengths provided by an attacker for variable-length string columns. By supplying a maliciously crafted FITS file, an attacker can overflow a fixed 28,800-byte stack buffer and the caller's string array, potentially enabling arbitrary code execution. This affects all versions of cfitsio up to and including 4.7.0.

Successful exploitation allows an attacker to execute arbitrary code on the system processing the malicious FITS file. This can lead to full compromise of the affected system or application using the vulnerable cfitsio library. The CVSS 4.0 base score is 8.5 (high severity), reflecting the local attack vector with low complexity, no privileges required, and high impact on confidentiality, integrity, and availability.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, avoid processing untrusted FITS files with vulnerable versions of cfitsio. Monitor vendor channels for updates and apply patches promptly once released.