Vulnerability in Theupdateframework Python-Tuf
CVE-2026-123806
python-tuf is a Python reference implementation of The Update Framework (TUF). Prior to 7.0.0, DelegatedRole._is_target_in_pathpattern in tuf/api/_payload.py uses fnmatch.fnmatch, which applies os.path.normcase before matching and makes delegation path authorization case-insensitive on Windows. When a TUF repository has path-based delegations that differ only by case and an attacker-controlled role is visited before the legitimate role, ngclient can accept an attacker-provided target from the wrong delegation for a requested path. Linux and macOS clients are not affected because their path normalization does not change case. This issue is fixed in 7.0.0.
Published .
CVSS v3 metric
CVSS v3 base score 4.0 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Theupdateframework Python-Tuf — versions < 7.0.0
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-123806?
- CVE-2026-123806 is a medium-severity vulnerability in Theupdateframework Python-Tuf, classified under Improper Handling of Case Sensitivity. CVSS score: 4.0/10. Published 2026-11-09.
- How severe is CVE-2026-123806?
- Medium severity. CVSS v3 base score is 4.0 out of 10.