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CVE-2026-123806

MEDIUMCVSS 4/10EPSS 0.13%

Last modified

CVE-2026-123806 is a medium-severity vulnerability rated 4/10 on the CVSS scale. 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. EPSS estimates a 0.13% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1
4/10

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS Probability
0.13%

2.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
theupdateframeworkpython-tuf< 7.0.0

References

Timeline

Published
Last Modified
Status
Awaiting Analysis

Frequently Asked Questions

What is 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.
How severe is CVE-2026-123806?
CVE-2026-123806 has a CVSS score of 4/10 (MEDIUM severity). The EPSS model estimates a 0.13% probability of exploitation in the next 30 days.
How do I fix CVE-2026-123806?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST