CVE-2026-46689 Kanidm: Unauthenticated process abort via SCIM filter stack exhaustion
Unauthenticated attackers can crash the Kanidm identity server by sending SCIM requests with deeply nested parentheses, causing a stack overflow.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-46689?
CVE-2026-46689 is a high-severity denial of service vulnerability in kanidm, published on 10 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Kanidm is an identity management platform. Prior to version 1.9.3, a single unauthenticated GET to any /scim/v1/... endpoint with a ?filter= query string of a few thousand nested parentheses (≈ 4–12 KB) drives the recursive-descent PEG parser past the worker thread's stack guard page. Rust responds to stack overflow with std::process::abort() — the entire kanidmd process exits. The parse runs inside axum's Query<ScimEntryGetQuery> extractor, before any handler body and therefore before any ACL check. This issue has been patched in version 1.9.3.
Which versions are affected by CVE-2026-46689?
4 open source packages ship an affected version, including kanidm_proto and scim_proto.
| Package | Affected | Fixed in |
|---|---|---|
kanidm_proto crates.io | All versions | 1.9.3 |
kanidm_proto crates.io | All versions | 1.9.3 |
scim_proto crates.io | All versions | 1.9.3 |
scim_proto crates.io | All versions | 1.9.3 |
How do I fix CVE-2026-46689?
Upgrade kanidm_proto to 1.9.3 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-46689 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-46689 exists.
Sources
Also known as GHSA-r5fr-9gmv-jggh.