CVE-2026-40110
HIGH7.3EPSS 0.01%Jupyter Server has a CORS Origin Validation Bypass via `re.match()` in `allow_origin_pat` (from huntr)
Description
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
Affected packages (2)
- Debian/jupyter-serverfrom 0
- PyPI/jupyter-serverfrom 0, < 2.18.0
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:L/SC:L/SI:L/SA:L |
| osv | CVSS 3.1 | HIGH7.3 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N |
References (7)
- ADVISORYhttps://nvd.nist.gov/vuln/detail/CVE-2026-40110
- ADVISORYhttps://security-tracker.debian.org/tracker/CVE-2026-40110
- PATCHhttps://github.com/jupyter-server/jupyter_server
- WEBhttps://github.com/jupyter-server/jupyter_server/commit/057869a327c46730afede3eab0ca2d2e3e74acea
- WEBhttps://github.com/jupyter-server/jupyter_server/commit/49b34392feaa97735b3b777e3baf8f22f2a14ed8
- WEBhttps://github.com/jupyter-server/jupyter_server/pull/603
- WEBhttps://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-24qx-w28j-9m6p