THREAT OPS › Threat News › [GHSA] GHSA-c3mw-737p-c7g2 (high) — Jupyter Server: 5xx request logging leaks token-bearing Referer header values
[GHSA] GHSA-c3mw-737p-c7g2 (high) — Jupyter Server: 5xx request logging leaks token-bearing Referer header values
GHSA-c3mw-737p-c7g2 Severity: high CVE: CVE-2026-86049
Jupyter Server: 5xx request logging leaks token-bearing Referer header values
### Summary
When a request returns a 500, `jupyter_server/log.py` logs a small JSON block of request headers.
The Referer header was copied into it as-is, so a token in the Referer URL ended up in the logs in plain text.
### Impact
Anyone who can read the serv
Indicators of compromise
- CVE-2026-86049cve
- http://127.0.0.1:8899/tree?token=REFERTOKENurl
- http://127.0.0.1:8899/api/kernels?token=VALIDTOKENurl
- http://127.0.0.1:8899/tree?token=url
Original source: https://github.com/advisories/GHSA-c3mw-737p-c7g2