# CVE-2026-25704: Incomplete privilege drop for com.system76.CosmicGreeter.GetUserData

> An attacker can exploit a race condition in cosmic-greeter to regain dropped privileges and escalate their access rights.

- **Severity:** Medium 5.8 (`CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 30 Mar 2026
- **Updated:** 16 Apr 2026
- **Also known as:** GHSA-h5vx-6jh5-qhq7

## What is CVE-2026-25704?

CVE-2026-25704 is a medium-severity vulnerability in pop-os cosmic-greeter, published on 30 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A Privilege Dropping / Lowering Errors/Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability in  cosmic-greeter can allow an attacker to regain privileges that should have been dropped and abuse them in the racy checking logic.

This issue affects cosmic-greeter before https://github.Com/pop-os/cosmic-greeter/pull/426.

Weakness: CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition), CWE-271 (Privilege Dropping / Lowering Errors)

## Which versions are affected by CVE-2026-25704?


## How do I fix CVE-2026-25704?

No fix has been published for CVE-2026-25704 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-25704 being exploited?

There is no known exploitation of CVE-2026-25704 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-25704 and fix it if it is affected.

What it is: CVE-2026-25704 is a medium-severity vulnerability in pop-os cosmic-greeter, published on 30 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-25704 in the wild and no public exploit code.

Affected product: pop-os cosmic-greeter. 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-2026-25704/ (Markdown: https://insights.sbomify.com/CVE-2026-25704/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-25704
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-25704
- OSV: https://osv.dev/vulnerability/CVE-2026-25704

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-25704/
Summaries are generated and may contain mistakes; the official description above is the record.