# CVE-2026-107585: Allocation of Resources Without Limits or Throttling in hMailServer

> Remote unauthenticated attackers can exhaust pending sign-in tables in hMailServer, causing denial of service for single sign-on and passkey authentication.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 8 Oct 2026
- **Updated:** 8 Oct 2026
- **Also known as:** GHSA-ff4v-mg5q-r7g9

## What is CVE-2026-107585?

CVE-2026-107585 is a medium-severity denial of service vulnerability in Progressive Robot Ltd hMailServer, published on 8 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Uncontrolled eviction in the pending sign-in tables of the REST API in Progressive Robot hMailServer 6.3.4 and 6.3.5 allows a remote unauthenticated attacker to make other users' OpenID Connect, SAML and passkey sign-ins fail. The routes that start a single sign-on and hand out a passkey sign-in challenge are reached without authentication and stored pending state in bounded tables that dropped their oldest entry when full, whoever had started it. An attacker who starts sign-ins a few times a second (about a hundred a second for passkeys) pushes every other user's pending sign-in out of the table before that user's browser returns, denying single sign-on and passkey sign-in for as long as the requests continue.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-107585?


## How do I fix CVE-2026-107585?

No fix has been published for CVE-2026-107585 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-107585 being exploited?

There is no known exploitation of CVE-2026-107585 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-107585 and fix it if it is affected.

What it is: CVE-2026-107585 is a medium-severity denial of service vulnerability in Progressive Robot Ltd hMailServer, published on 8 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-107585 in the wild and no public exploit code.

Affected product: Progressive Robot Ltd hMailServer. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-107585/ (Markdown: https://insights.sbomify.com/CVE-2026-107585/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-107585
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-107585
- OSV: https://osv.dev/vulnerability/CVE-2026-107585

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-107585/
Summaries are generated and may contain mistakes; the official description above is the record.