A critical flaw in IBM Sterling File Gateway lets an unauthenticated remote attacker forge an SSO header and obtain a fully authenticated session.
What Is It
CVE-2026-75878 is an improper authentication vulnerability (CWE-287) in IBM Sterling File Gateway. According to IBM's advisory, the product fails to validate an SSO header, allowing a remote attacker to bypass authentication entirely and obtain a fully authenticated session.
The issue carries a CVSS 3.1 base score of 9.1 (Critical) with vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N, network-reachable, low attack complexity, no privileges, and no user interaction required, with high confidentiality and integrity impact.
Why It Matters
An authentication bypass on a managed file transfer platform is about as direct as an attack path gets. There is no exploit chain to build and no credential to phish: a crafted request header is sufficient to land inside the application as an authenticated user. The CVSS breakdown reflects that; an exploitability subscore of 3.9, the maximum, paired with an impact subscore of 5.2 covering high confidentiality and integrity loss.
Sterling File Gateway handles partner-to-partner file exchange, so a session obtained this way sits directly on top of the data moving through it.
This CVE does not currently appear in the CISA Known Exploited Vulnerabilities catalog, and no confirmation of active exploitation is present in the supplied data.
What's Vulnerable
IBM lists Sterling File Gateway affected from version 6.2.0.0 across the following ranges:
- 6.2.0.0 through 6.2.0.6_1
- 6.2.1.0 through 6.2.1.2
- 6.2.2.0 through 6.2.2.1
Patch Status
The CVE record was published 2026-09-18 by IBM PSIRT and remains in NVD status Received, meaning NVD enrichment is not yet complete. No fixed-version details or required-action deadlines are included in the supplied data. Refer to IBM's advisory (linked below) for remediation guidance and fix packs.
Sources
- NVD, CVE-2026-75878: https://nvd.nist.gov/vuln/detail/CVE-2026-75878
- IBM Support Advisory ([email protected]): https://www.ibm.com/support/pages/node/7287497