Answer in brief
CVE-2026-6657 records a High severity (CVSS 8.8) rce vulnerability in Duplicate Advisory: jupyter-server is vulnerable to CORS origin validation bypass when the `allow_origin_pat` configuration is used. The source record does not mark it as known exploited. 1 affected package is mapped in the feed.
Answer in brief
CVE-2026-6657 records a High severity (CVSS 8.8) rce vulnerability in Duplicate Advisory: jupyter-server is vulnerable to CORS origin validation bypass when the `allow_origin_pat` configuration is used. The source record does not mark it as known exploited. 1 affected package is mapped in the feed.
Monitor this advisory for an available fix and review any installs of the affected package.
Local check
hol-guard supply-chain scanRCE describes the vulnerability class recorded for this advisory. The current record does not mark CVE-2026-6657 as known exploited; continue to monitor the source for status changes. The feed includes package mappings that can be checked against lockfiles and deployed manifests.
| Package | Affected range | Fixed version |
|---|---|---|
| jupyter-serverpip | >=1.12.0,<=2.17.0 | Not reported |
Reported by GitHub Security Advisories (ghsa).
CVE-2026-6657 records a High severity (CVSS 8.8) rce vulnerability in Duplicate Advisory: jupyter-server is vulnerable to CORS origin validation bypass when the `allow_origin_pat` configuration is used. The source record does not mark it as known exploited. 1 affected package is mapped in the feed.
The source record does not mark it as known exploited.
Check lockfiles and deployed manifests for jupyter-server.
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL GuardMonitor this advisory for an available fix and review any installs of the affected package.
Local check
hol-guard supply-chain scanRCE describes the vulnerability class recorded for this advisory. The current record does not mark CVE-2026-6657 as known exploited; continue to monitor the source for status changes. The feed includes package mappings that can be checked against lockfiles and deployed manifests.
| Package | Affected range | Fixed version |
|---|---|---|
| jupyter-serverpip | >=1.12.0,<=2.17.0 | Not reported |
Reported by GitHub Security Advisories (ghsa).
CVE-2026-6657 records a High severity (CVSS 8.8) rce vulnerability in Duplicate Advisory: jupyter-server is vulnerable to CORS origin validation bypass when the `allow_origin_pat` configuration is used. The source record does not mark it as known exploited. 1 affected package is mapped in the feed.
The source record does not mark it as known exploited.
Check lockfiles and deployed manifests for jupyter-server.
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL Guard### Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-24qx-w28j-9m6p. This link is maintained to preserve external references. ### Original Description A vulnerability in jupyter-server versions 1.12.0 through 2.17.0 allows an attacker to bypass CORS origin validation when the `allow_origin_pat` configuration is used. The issue arises from the use of `re.match()` for validating the `Origin` header, which only anchors at the start of the string. This allows attacker-controlled domains such as `trusted.example.com.evil.com` to pass validation against patterns intended to match `trusted.example.com`. The vulnerability affects multiple locations in the codebase, including CORS headers, WebSocket connections, referer validation, and login redirects, potentially enabling phishing attacks, arbitrary code execution, and unauthorized access to sensitive API responses.
### Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-24qx-w28j-9m6p. This link is maintained to preserve external references. ### Original Description A vulnerability in jupyter-server versions 1.12.0 through 2.17.0 allows an attacker to bypass CORS origin validation when the `allow_origin_pat` configuration is used. The issue arises from the use of `re.match()` for validating the `Origin` header, which only anchors at the start of the string. This allows attacker-controlled domains such as `trusted.example.com.evil.com` to pass validation against patterns intended to match `trusted.example.com`. The vulnerability affects multiple locations in the codebase, including CORS headers, WebSocket connections, referer validation, and login redirects, potentially enabling phishing attacks, arbitrary code execution, and unauthorized access to sensitive API responses.