# CVE-2026-82735: Match regex runs on over-length input in Ash.Type.String, enabling regex denial of service

> Attackers can cause CPU exhaustion by sending over-length input to Ash.Type.String, bypassing length checks before regex evaluation.

- **Severity:** Medium 5.9 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 1 Sep 2026
- **Updated:** 1 Sep 2026
- **Also known as:** EEF-CVE-2026-82735, GHSA-mq7g-pffw-m8xh

## What is CVE-2026-82735?

CVE-2026-82735 is a medium-severity denial of service vulnerability in ash-project ash, published on 1 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Uncontrolled Resource Consumption vulnerability in ash-project ash allows an attacker to force an expensive regular expression to run on input that a length constraint should have already rejected.

Ash.Type.String.apply_constraints/2 (lib/ash/type/string.ex) evaluated the :match regex regardless of the min_length and max_length constraints on the same attribute. Because the length check did not gate the regex, an over-length value that the length constraint rejects still had the pattern applied to it, so the length limit that would otherwise bound the work never constrained the regex input. Against a backtracking pattern this yields catastrophic regex evaluation on attacker-sized input, and even a linear pattern runs on arbitrarily large input, consuming CPU per request. The fix skips the :match regex whenever a length constraint is violated, making the two checks order-independent.

This issue affects ash: from 0.10.0 before 3.32.2.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-82735?

1 open source package ship an affected version, including ash.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `ash` | Hex | From 0.10.0 | 3.32.2 |

## How do I fix CVE-2026-82735?

Upgrade ash to 3.32.2 or later.

## Is CVE-2026-82735 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-82735 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-82735 and fix it if it is affected.

What it is: CVE-2026-82735 is a medium-severity denial of service vulnerability in ash-project ash, published on 1 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-82735 exists.

Affected packages and fixed versions:
- ash (Hex): affected from 0.10.0; fixed in 3.32.2

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-82735/ (Markdown: https://insights.sbomify.com/CVE-2026-82735/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-82735
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-82735
- OSV: https://osv.dev/vulnerability/CVE-2026-82735

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-82735/
Summaries are generated and may contain mistakes; the official description above is the record.