{"id":"CVE-2026-123806","aliases":["EUVD-2026-120403","GHSA-qp9x-wp8f-qgjj","UBUNTU-CVE-2026-123806"],"status":"published","title":"python-tuf: Platform-dependent delegation path matching","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.","severity":{"version":"3.1","score":4,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00133,"percentile":0.02895,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-178"],"published":"2026-05-28T22:46:13Z","modified":"2026-11-11T09:39:20Z","fixes":[{"ecosystem":"PyPI","package":"tuf","fixed_in":["7.0.0"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"tuf","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"6.0.0"},{"fixed":"7.0.0"}]}]},{"source":"osv","ecosystem":"PyPI","package":"tuf","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"7.0.0"}]}],"versions":["0.10.0","0.10.1","0.10.2","0.11.0","0.11.1","0.11.2.dev1","0.11.2.dev2","0.11.2.dev3","0.11.dev0","0.12.0","0.12.1","0.12.2","0.12.dev0","0.12.dev1","0.12.dev2","0.13.0","0.14.0","0.15.0","0.16.0","0.17.0","0.18.0","0.18.1","0.19.0","0.20.0","0.7.5","0.9.8","0.9.9","1.0.0","1.1.0","2.0.0","2.1.0","3.0.0","3.1.0","3.1.1","4.0.0","5.0.0","5.1.0","6.0.0"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"python-tuf","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["6.0.0-2","7.0.0-1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"python-tuf","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["5.1.0-2","6.0.0-2"]}],"products":[{"vendor":"theupdateframework","product":"python-tuf"}],"references":[{"url":"https://github.com/theupdateframework/python-tuf/security/advisories/GHSA-qp9x-wp8f-qgjj","tags":["x_refsource_CONFIRM","advisory","web"]},{"url":"https://github.com/theupdateframework/python-tuf/commit/8ed4414946041030b264871ac41b929cf15774a5","tags":["x_refsource_MISC","fix"]},{"url":"https://github.com/theupdateframework/python-tuf/releases/tag/v7.0.0","tags":["x_refsource_MISC","web"]},{"url":"https://github.com/advisories/GHSA-qp9x-wp8f-qgjj"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/123xxx/CVE-2026-123806.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-123806","tags":["advisory"]},{"url":"https://github.com/theupdateframework/python-tuf","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2026-123806","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-123806","tags":["report"]},{"url":"github.com/theupdateframework/python-tuf","tags":["report"]},{"url":"github.com/theupdateframework/python-tuf/releases/tag/v7.0.0","tags":["report"]},{"url":"github.com/theupdateframework/python-tuf/security/advisories/ghsa-qp9x-wp8f-qgjj","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-123806","title":"python-tuf: Platform-dependent delegation path matching","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.","status":"published","published":"2026-11-09T20:18:45.481Z","modified":"2026-11-09T20:18:45.481Z","cvss":[{"version":"3.1","score":4,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-178"],"updated_at":"2026-11-09T21:34:55.566109Z"}],"euvd":[{"id":"EUVD-2026-120403","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.","status":"published","published":"2026-11-09T20:18:45Z","modified":"2026-11-09T20:18:45Z","cvss":[{"version":"3.1","score":4,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium"}],"updated_at":"2026-11-09T21:18:10.039091Z"}],"ghsa":[{"id":"GHSA-qp9x-wp8f-qgjj","title":"tuf has platform-dependent delegation path matching","description":"`DelegatedRole._is_target_in_pathpattern` uses `fnmatch.fnmatch` to decide whether a given target path is authorized by a delegation's glob pattern.\n\nPython's `fnmatch.fnmatch` calls `os.path.normcase()` on both arguments before matching. On POSIX hosts `normcase` is the identity function; on Windows hosts `os.path` resolves to `ntpath`, whose `normcase` lowercases its input and replaces `/` with `\\`.\n\nAs a result, python-tuf's delegation *path pattern* matching is case-sensitive on Linux/macOS but case-INSENSITIVE on Windows. This makes the authorization decision for a target dependent on the host operating system of the client running the updater.\n\nThe result on Windows is a TUF specification violation in the python-tuf `ngclient` implementation.\n\n## Vulnerable code\n\n`tuf/api/_payload.py` (HEAD `7ecb67d`):\n\n```python\n1183  @staticmethod\n1184  def _is_target_in_pathpattern(targetpath: str, pathpattern: str) -\u003e bool:\n1185      \"\"\"Determine whether ``targetpath`` matches the ``pathpattern``.\"\"\"\n1186      # We need to make sure that targetpath and pathpattern are pointing to\n1187      # the same directory as fnmatch doesn't threat \"/\" as a special symbol.\n1188      target_parts = targetpath.split(\"/\")\n1189      pattern_parts = pathpattern.split(\"/\")\n1190      if len(target_parts) != len(pattern_parts):\n1191          return False\n1192\n1193      # Every part in the pathpattern could include a glob pattern, that's why\n1194      # each of the target and pathpattern parts should match.\n1195      for target, pattern in zip(target_parts, pattern_parts, strict=True):\n1196          if not fnmatch.fnmatch(target, pattern):\n1197              return False\n1198      return True\n```\n\n`fnmatch.fnmatch` source (Python 3.12, unchanged in current mainline):\n\n```python\ndef fnmatch(name, pat):\n    ...\n    name = os.path.normcase(name)\n    pat = os.path.normcase(pat)\n    return fnmatchcase(name, pat)\n```\n\n## Fix\n\nReplace `fnmatch.fnmatch` with `fnmatch.fnmatchcase`, which is explicitly documented as \"not applying case normalization\", so it behaves identically across platforms.\n\n## Attack\n\n1. A TUF repository with two path-based delegations whose patterns differ only in case — for example, `Foo/*` and `foo/*`.\n2. The \"attacker\" delegation is listed BEFORE the \"legit\" delegation in the delegation order.\n3. The client searches for `foo/something`: on Windows, it will find the \"attacker\" provided target \"Foo/something\".\n\n\n## Exploitability caveats \n\n* The attack needs a repository configuration with case-colliding delegation path patterns. The attacker must control one of the delegated roles.\n* Delegation ordering matters: the attacker-controlled role must be visited BEFORE the legit role in the pre-order walk.\n* The client must run on Windows. No effect on Linux/macOS.\n\n## Credit\n\nReporter: Koda Reef @kodareef5 \nAdvisory edits: Jussi Kukkonen @jku","status":"published","published":"2026-05-28T22:46:13Z","modified":"2026-11-09T20:18:56Z","cvss":[{"version":"3.1","score":4,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium"}],"cwes":["CWE-178"],"updated_at":"2026-11-09T20:19:39.584745Z"}],"nvd":[{"id":"CVE-2026-123806","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.","status":"published","published":"2026-11-09T22:18:36.503Z","modified":"2026-11-09T22:18:36.503Z","cvss":[{"version":"3.1","score":4,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-178"],"updated_at":"2026-11-09T23:16:05.865626Z"}],"osv":[{"id":"CVE-2026-123806","title":"python-tuf: Platform-dependent delegation path matching","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.","status":"published","published":"2026-11-09T20:18:45.481Z","modified":"2026-11-11T02:48:45.466515955Z","cvss":[{"version":"3.1","score":4,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium"}],"cwes":["CWE-178"],"updated_at":"2026-11-11T03:22:00.901153Z"},{"id":"GHSA-qp9x-wp8f-qgjj","title":"tuf has platform-dependent delegation path matching","description":"`DelegatedRole._is_target_in_pathpattern` uses `fnmatch.fnmatch` to decide whether a given target path is authorized by a delegation's glob pattern.\n\nPython's `fnmatch.fnmatch` calls `os.path.normcase()` on both arguments before matching. On POSIX hosts `normcase` is the identity function; on Windows hosts `os.path` resolves to `ntpath`, whose `normcase` lowercases its input and replaces `/` with `\\`.\n\nAs a result, python-tuf's delegation *path pattern* matching is case-sensitive on Linux/macOS but case-INSENSITIVE on Windows. This makes the authorization decision for a target dependent on the host operating system of the client running the updater.\n\nThe result on Windows is a TUF specification violation in the python-tuf `ngclient` implementation.\n\n## Vulnerable code\n\n`tuf/api/_payload.py` (HEAD `7ecb67d`):\n\n```python\n1183  @staticmethod\n1184  def _is_target_in_pathpattern(targetpath: str, pathpattern: str) -\u003e bool:\n1185      \"\"\"Determine whether ``targetpath`` matches the ``pathpattern``.\"\"\"\n1186      # We need to make sure that targetpath and pathpattern are pointing to\n1187      # the same directory as fnmatch doesn't threat \"/\" as a special symbol.\n1188      target_parts = targetpath.split(\"/\")\n1189      pattern_parts = pathpattern.split(\"/\")\n1190      if len(target_parts) != len(pattern_parts):\n1191          return False\n1192\n1193      # Every part in the pathpattern could include a glob pattern, that's why\n1194      # each of the target and pathpattern parts should match.\n1195      for target, pattern in zip(target_parts, pattern_parts, strict=True):\n1196          if not fnmatch.fnmatch(target, pattern):\n1197              return False\n1198      return True\n```\n\n`fnmatch.fnmatch` source (Python 3.12, unchanged in current mainline):\n\n```python\ndef fnmatch(name, pat):\n    ...\n    name = os.path.normcase(name)\n    pat = os.path.normcase(pat)\n    return fnmatchcase(name, pat)\n```\n\n## Fix\n\nReplace `fnmatch.fnmatch` with `fnmatch.fnmatchcase`, which is explicitly documented as \"not applying case normalization\", so it behaves identically across platforms.\n\n## Attack\n\n1. A TUF repository with two path-based delegations whose patterns differ only in case — for example, `Foo/*` and `foo/*`.\n2. The \"attacker\" delegation is listed BEFORE the \"legit\" delegation in the delegation order.\n3. The client searches for `foo/something`: on Windows, it will find the \"attacker\" provided target \"Foo/something\".\n\n\n## Exploitability caveats \n\n* The attack needs a repository configuration with case-colliding delegation path patterns. The attacker must control one of the delegated roles.\n* Delegation ordering matters: the attacker-controlled role must be visited BEFORE the legit role in the pre-order walk.\n* The client must run on Windows. No effect on Linux/macOS.\n\n## Credit\n\nReporter: Koda Reef @kodareef5 \nAdvisory edits: Jussi Kukkonen @jku","status":"published","published":"2026-05-28T22:46:13Z","modified":"2026-11-09T20:30:04.18706512Z","cvss":[{"version":"3.1","score":4,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium"}],"cwes":["CWE-178"],"updated_at":"2026-11-09T20:39:59.362871Z"},{"id":"UBUNTU-CVE-2026-123806","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.","status":"published","published":"2026-05-28T22:46:13Z","modified":"2026-11-12T17:25:21.660130807Z","cvss":[{"version":"3.1","score":4,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium"},{"version":"3.1","score":4,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium"},{"version":"3.1","score":4,"vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium"}],"updated_at":"2026-11-12T18:05:20.870791Z"}]}}