Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Heimdall versions before 0.17.17 are vulnerable when running in proxy mode. The Forwarded header is built from the incoming Host header without removing commas or semicolons, so an attacker who can send requests can inject extra Forwarded parameters and spoof the client IP seen by upstream services that trust that header, potentially bypassing IP-based access controls. Upgrade to Heimdall 0.17.17 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 |
|---|---|---|---|---|
| 7.0 | High | 4.0 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0049, the 42nd percentile, on 13 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 15:05 UTC First seen by agentprime
- 31 Oct 2026, 15:05 UTC Confirmed by OSV