# CVE-2021-25263: Privilege escalation in Yandex Browser (Desktop)

> Local attackers can execute arbitrary code with SYSTEM privileges by manipulating files during the Yandex Browser update process due to insecure directory permissions.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 17 Aug 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-37r4-xgj4-h786

## What is CVE-2021-25263?

CVE-2021-25263 is a high-severity vulnerability in Yandex Browser (Desktop), published on 17 Aug 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Local privilege vulnerability in Yandex Browser for Windows prior to 21.9.0.390 allows a local, low privileged, attacker to execute arbitary code with the SYSTEM privileges through manipulating files in directory with insecure permissions during Yandex Browser update process.

Weakness: CWE-732 (Incorrect Permission Assignment for Critical Resource)

## Which versions are affected by CVE-2021-25263?

It affects 1 product.


Products: Yandex Yandex Browser.

## How do I fix CVE-2021-25263?

No fix has been published for CVE-2021-25263 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-25263 being exploited?

There is no known exploitation of CVE-2021-25263 in the wild and no public exploit code.

## Other vulnerabilities in Yandex Browser (Desktop)

- [CVE-2024-6473](https://insights.sbomify.com/CVE-2024-6473/): DLL Hijacking in Yandex Browser (high 8.4)
- [CVE-2021-25255](https://insights.sbomify.com/CVE-2021-25255/): Yandex Browser Lite for Android prior to version 21.1.0 allows remote attackers to cause a denial of service. (high 8.3)
- [CVE-2021-25254](https://insights.sbomify.com/CVE-2021-25254/): Yandex Browser Lite for Android before 21.1.0 allows remote attackers to spoof the address bar. (high 8.2)
- [CVE-2021-25261](https://insights.sbomify.com/CVE-2021-25261/): Privilege escalation in Yandex Browser (Desktop) (high 7.8)
- [CVE-2022-28225](https://insights.sbomify.com/CVE-2022-28225/): Privilege escalation in Yandex Browser (Desktop) (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-25263 and fix it if it is affected.

What it is: CVE-2021-25263 is a high-severity vulnerability in Yandex Browser (Desktop), published on 17 Aug 2021. 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-2021-25263 in the wild and no public exploit code.

Affected product: Yandex Browser (Desktop). 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-2021-25263/ (Markdown: https://insights.sbomify.com/CVE-2021-25263/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-25263
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-25263
- OSV: https://osv.dev/vulnerability/CVE-2021-25263

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-25263/
Summaries are generated and may contain mistakes; the official description above is the record.