GHSA-24qx-w28j-9m6p
Jupyter Server has a CORS Origin Validation Bypass via `re.match()` in `allow_origin_pat`
Packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| PyPI | jupyter-server | < 2.18.0 | 2.18.0 |
Details
As written in the advisory (Markdown source, shown as plain text).
Jupyter Server uses `re.match()` to validate the Origin header against the `allow_origin_pat` configuration.
Since `re.match()` only anchors at the start of the string, an attacker who controls a domain like `http://trusted.example.com.evil.com/` passes validation against a pattern intended to match only `trusted.example.com`.
### Impact
<=2.17.0
### Patches
057869a327c46730afede3eab0ca2d2e3e74acea, 49b34392feaa97735b3b777e3baf8f22f2a14ed8
### Workarounds
Wrap your `allow_origin_pat` value with `^` and `$`
### References
https://github.com/jupyter-server/jupyter_server/pull/603
https://docs.python.org/3/library/re.html#re.fullmatch
https://docs.python.org/3/library/re.html#re.match
References
External links from the advisory. They lead to third-party sites.
- https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-24qx-w28j-9m6p
- https://nvd.nist.gov/vuln/detail/CVE-2026-40110
- https://github.com/jupyter-server/jupyter_server/pull/603
- https://github.com/jupyter-server/jupyter_server/commit/057869a327c46730afede3eab0ca2d2e3e74acea
- https://github.com/jupyter-server/jupyter_server/commit/49b34392feaa97735b3b777e3baf8f22f2a14ed8
- https://access.redhat.com/errata/RHSA-2026:43038
- https://access.redhat.com/security/cve/CVE-2026-40110
- https://bugzilla.redhat.com/show_bug.cgi?id=2466912
- https://github.com/jupyter-server/jupyter_server
- https://github.com/pypa/advisory-database/tree/main/vulns/jupyter-server/PYSEC-2026-2187.yaml
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40110.json