scim_proto and kanidm_proto have an authenticated process abort via SCIM filter stack exhaustion

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.7 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-46689: 0.32% estimated exploitation activity in the next 30 days; percentile 24.66 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary 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. Details The SCIM filter grammar recurses on ( and not ( with no depth bound. proto/src/scimv1/mod.rs:263-433 — peg::parser! { grammar scimfilter() ... }: Both rules re-enter parse() without a depth counter. proto/src/scimv1/mod.rs:442-447 — impl FromStr for ScimFilter calls scimfilter::parse(input) directly on the raw string with no length or depth pre-check. proto/src/scimv1/mod.rs:80-81 — ScimEntryGetQuery.filter is #[serdeas(as = "Option<DisplayFromStr")], so deserialising the query struct invokes ScimFilter::fromstr on attacker bytes.…

Published by the source

6 May 2026, 23:38 UTC

Last modified by the source

29 Jun 2026, 15:30 UTC

Source last checked

26 Oct 2026, 15:42 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-r5fr-9gmv-jggh

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# Patch Next advisory brief: CVE-2026-46689

Advisory: scim_proto and kanidm_proto have an authenticated process abort via SCIM filter stack exhaustion
IDs: CVE-2026-46689, GHSA-r5fr-9gmv-jggh
Record: https://patchnext.com/advisories/cve-2026-46689 (revision 1, source checked 26 Oct 2026, 15:42 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: kanidm_proto 1.9.3; scim_proto 1.9.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io kanidm_proto: affected <= 1.9.2; fixed in 1.9.3
- crates.io scim_proto: affected <= 1.9.2; fixed in 1.9.3

## Suggested inspection (read-only)
- crates.io kanidm_proto: check the installed version with your package manager.
- crates.io scim_proto: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on kanidm_proto, scim_proto.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-r5fr-9gmv-jggh (GitHub-reviewed advisory GHSA-r5fr-9gmv-jggh lists affected ranges: crates.io scim_proto >=0 =0 <=1.9.2)

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