Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Werkzeug versions before 3.1.5 have a flaw in safe_join, which does not reject Windows device names such as CON or AUX when they carry a file extension or trailing spaces. The source says that when an application on Windows uses send_from_directory and a requested path ends in such a name, reading the file hangs indefinitely; the attacker needs only to be able to request a path from that application. Upgrade to Werkzeug 3.1.5 or later.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 6.3 | Medium | 4.0 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0047, the 41st percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 14:34 UTC First seen by agentprime
- 31 Oct 2026, 14:34 UTC Confirmed by OSV