VulnerabilityPublished 9 Nov 2026

CVE-2026-123806: theupdateframework python-tuf · Improper Handling of Case Sensitivity

Affects theupdateframework python-tufSource CVE Database V5

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Not known to be exploited · CVSS 4.0 Medium : upgrade to 7.0.0 when convenient.

Data as of 9 Nov 2026, 20:34 UTC

CVSS 3.1 base score

4.0Medium

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 3.1	4.0

Patch: Available – fixed in 7.0.0

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

Attack Vector: Local
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 9 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 9 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade theupdateframework python-tuf to 7.0.0.

Affected software

Product	Affected	Fixed in
theupdateframeworkpython-tuf	Affected <7.0.0	Fixed in 7.0.0

AI-suggested

Upgrade python-tuf to version 7.0.0 or later, where the issue is fixed. No other mitigation is necessary as the vulnerability is resolved by this official fix.

Description

python-tuf versions prior to 7.0.0 have a case sensitivity handling flaw in delegated role path authorization on Windows. This allows an attacker to exploit path-based delegations that differ only by case, potentially causing the client to accept a malicious target from an incorrect delegation. Linux and macOS clients are not affected. The issue is fixed in version 7.0.0.

Impact

On Windows systems using python-tuf versions before 7.0.0, an attacker can exploit case-insensitive path matching to cause the client to accept malicious targets from unauthorized delegations. This impacts the integrity of the update process by allowing injection of attacker-controlled content. There is no impact on confidentiality or availability, and Linux/macOS clients are unaffected.

Summary

The vulnerability in python-tuf (CVE-2026-123806) arises from the use of fnmatch.fnmatch in DelegatedRole._is_target_in_pathpattern, which applies os.path.normcase on Windows, making path authorization case-insensitive. When a TUF repository contains delegations differing only by case, an attacker-controlled role visited before the legitimate role can cause ngclient to accept an attacker-provided target for a requested path. This flaw does not affect Linux or macOS clients due to their case-preserving path normalization. The problem is resolved in python-tuf version 7.0.0.

CWE-178Improper Handling of Case Sensitivity (opens in a new tab)
Base weakness
The product does not properly account for differences in case sensitivity when accessing or determining the properties of a resource, leading to inconsistent results.
Architecture and Design · Input Validation
Avoid making decisions based on names of resources (e.g. files) if those resources can have alternate names.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Implementation · Input Validation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174).
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 9 Nov 2026, 20:34 UTC

WeaknessesCWE-178

Technical details

References

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