### Summary Jupyter Server <=2.17.0 can access directories sibling to the root directory, if it starts with the root dir's name. ### PoC Minimal: ``` . ├── test/ <- root directory. │ └── test.txt └── testtest/ └── secret.txt <- file to exfiltrate that we should not be able to access via API ``` ```bash HOST="http://localhost:8888" TOKEN="" SIBLING="testtest" TARGET="secret.txt" curl -s -X POST \ "$HOST/api/contents/%2e%2e/$SIBLING/$TARGET/checkpoints" \ -H "Authorization: token $TOKEN" ``` Full PoC by @stef41: https://gist.github.com/Yann-P/66d4982a965dee8fcb8dd89db29e7006 ### Impact It is possible for an authenticated user to access content outside the server's `root_dir` in siblings directories sharing the same prefix as the `root_dir`. The attacker can escalate access, reading, writing, and deleting from sibling directories. This can have a tangible impact for deployments using predictable naming scheme with multi-tenant server, for example `user1`, `user2`, `user3`, ..., `user10` etc, as `user1` could access and modify files of all `user10` - `user19` and higher. In a hypothetical system where users can choose a name of their folder, an attacker could choose a single-letter username to gain access to a significant number of sibling directories. ### Workarounds Use folder names that do not overlap. ### Acknowledgments Thank you to @stef41 for providing a useful PoC.
### Summary Jupyter Server <=2.17.0 can access directories sibling to the root directory, if it starts with the root dir's name. ### PoC Minimal: ``` . ├── test/ <- root directory. │ └── test.txt └── testtest/ └── secret.txt <- file to exfiltrate that we should not be able to access via API ``` ```bash HOST="http://localhost:8888" TOKEN="" SIBLING="testtest" TARGET="secret.txt" curl -s -X POST \ "$HOST/api/contents/%2e%2e/$SIBLING/$TARGET/checkpoints" \ -H "Authorization: token $TOKEN" ``` Full PoC by @stef41: https://gist.github.com/Yann-P/66d4982a965dee8fcb8dd89db29e7006 ### Impact It is possible for an authenticated user to access content outside the server's `root_dir` in siblings directories sharing the same prefix as the `root_dir`. The attacker can escalate access, reading, writing, and deleting from sibling directories. This can have a tangible impact for deployments using predictable naming scheme with multi-tenant server, for example `user1`, `user2`, `user3`, ..., `user10` etc, as `user1` could access and modify files of all `user10` - `user19` and higher. In a hypothetical system where users can choose a name of their folder, an attacker could choose a single-letter username to gain access to a significant number of sibling directories. ### Workarounds Use folder names that do not overlap. ### Acknowledgments Thank you to @stef41 for providing a useful PoC.
### Summary Jupyter Server <=2.17.0 can access directories sibling to the root directory, if it starts with the root dir's name. ### PoC Minimal: ``` . ├── test/ <- root directory. │ └── test.txt └── testtest/ └── secret.txt <- file to exfiltrate that we should not be able to access via API ``` ```bash HOST="http://localhost:8888" TOKEN="" SIBLING="testtest" TARGET="secret.txt" curl -s -X POST \ "$HOST/api/contents/%2e%2e/$SIBLING/$TARGET/checkpoints" \ -H "Authorization: token $TOKEN" ``` Full PoC by @stef41: https://gist.github.com/Yann-P/66d4982a965dee8fcb8dd89db29e7006 ### Impact It is possible for an authenticated user to access content outside the server's `root_dir` in siblings directories sharing the same prefix as the `root_dir`. The attacker can escalate access, reading, writing, and deleting from sibling directories. This can have a tangible impact for deployments using predictable naming scheme with multi-tenant server, for example `user1`, `user2`, `user3`, ..., `user10` etc, as `user1` could access and modify files of all `user10` - `user19` and higher. In a hypothetical system where users can choose a name of their folder, an attacker could choose a single-letter username to gain access to a significant number of sibling directories. ### Workarounds Use folder names that do not overlap. ### Acknowledgments Thank you to @stef41 for providing a useful PoC.
### Summary Jupyter Server <=2.17.0 can access directories sibling to the root directory, if it starts with the root dir's name. ### PoC Minimal: ``` . ├── test/ <- root directory. │ └── test.txt └── testtest/ └── secret.txt <- file to exfiltrate that we should not be able to access via API ``` ```bash HOST="http://localhost:8888" TOKEN="" SIBLING="testtest" TARGET="secret.txt" curl -s -X POST \ "$HOST/api/contents/%2e%2e/$SIBLING/$TARGET/checkpoints" \ -H "Authorization: token $TOKEN" ``` Full PoC by @stef41: https://gist.github.com/Yann-P/66d4982a965dee8fcb8dd89db29e7006 ### Impact It is possible for an authenticated user to access content outside the server's `root_dir` in siblings directories sharing the same prefix as the `root_dir`. The attacker can escalate access, reading, writing, and deleting from sibling directories. This can have a tangible impact for deployments using predictable naming scheme with multi-tenant server, for example `user1`, `user2`, `user3`, ..., `user10` etc, as `user1` could access and modify files of all `user10` - `user19` and higher. In a hypothetical system where users can choose a name of their folder, an attacker could choose a single-letter username to gain access to a significant number of sibling directories. ### Workarounds Use folder names that do not overlap. ### Acknowledgments Thank you to @stef41 for providing a useful PoC.
Update jupyter-server to 2.18.0 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanJupyter Server: Path Traversal via incorrect startswith() root directory check allows access to sibling directories affects jupyter-server (pip). Severity is high. ### Summary Jupyter Server <=2.17.0 can access directories sibling to the root directory, if it starts with the root dir's name. ### PoC Minimal: ``` . ├── test/ <- root directory. │ └── test.txt └── testtest/ └── secret.txt <- file to exfiltrate that we should not be able to access via API ``` ```bash HOST="http://localhost:8888" TOKEN="" SIBLING="testtest" TARGET="secret.txt" curl -s -X POST \ "$HOST/api/contents/%2e%2e/$SIBLING/$TARGET/checkpoints" \ -H "Authorization: token $TOKEN" ``` Full PoC by @stef41: https://gist.github.com/Yann-P/66d4982a965dee8fcb8dd89db29e7006 ### Impact It is possible for an authenticated user to access content outside the server's `root_dir` in siblings directories sharing the same prefix as the `root_dir`. The attacker can escalate access, reading, writing, and deleting from sibling directories. This can have a tangible impact for deployments using predictable naming scheme with multi-tenant server, for example `user1`, `user2`, `user3`, ..., `user10` etc, as `user1` could access and modify files of all `user10` - `user19` and higher. In a hypothetical system where users can choose a name of their folder, an attacker could choose a single-letter username to gain access to a significant number of sibling directories. ### Workarounds Use folder names that do not overlap. ### Acknowledgments Thank you to @stef41 for providing a useful PoC.
AI coding agents often install or upgrade packages automatically in pip. A high vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| jupyter-serverpip | <=2.17.0 | 2.18.0 |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL GuardUpdate jupyter-server to 2.18.0 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanJupyter Server: Path Traversal via incorrect startswith() root directory check allows access to sibling directories affects jupyter-server (pip). Severity is high. ### Summary Jupyter Server <=2.17.0 can access directories sibling to the root directory, if it starts with the root dir's name. ### PoC Minimal: ``` . ├── test/ <- root directory. │ └── test.txt └── testtest/ └── secret.txt <- file to exfiltrate that we should not be able to access via API ``` ```bash HOST="http://localhost:8888" TOKEN="" SIBLING="testtest" TARGET="secret.txt" curl -s -X POST \ "$HOST/api/contents/%2e%2e/$SIBLING/$TARGET/checkpoints" \ -H "Authorization: token $TOKEN" ``` Full PoC by @stef41: https://gist.github.com/Yann-P/66d4982a965dee8fcb8dd89db29e7006 ### Impact It is possible for an authenticated user to access content outside the server's `root_dir` in siblings directories sharing the same prefix as the `root_dir`. The attacker can escalate access, reading, writing, and deleting from sibling directories. This can have a tangible impact for deployments using predictable naming scheme with multi-tenant server, for example `user1`, `user2`, `user3`, ..., `user10` etc, as `user1` could access and modify files of all `user10` - `user19` and higher. In a hypothetical system where users can choose a name of their folder, an attacker could choose a single-letter username to gain access to a significant number of sibling directories. ### Workarounds Use folder names that do not overlap. ### Acknowledgments Thank you to @stef41 for providing a useful PoC.
AI coding agents often install or upgrade packages automatically in pip. A high vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| jupyter-serverpip | <=2.17.0 | 2.18.0 |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL Guard