# CVE-2021-43795: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') in com.linecorp.armeria:armeria

> An attacker can read arbitrary files from the server's local file system by bypassing path validation using encoded slashes in HTTP requests.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 2 Dec 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-8fp4-rp6c-5gcv, ROOT-APP-MAVEN-CVE-2021-43795

## What is CVE-2021-43795?

CVE-2021-43795 is a high-severity path traversal vulnerability in line armeria, published on 2 Dec 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Armeria is an open source microservice framework. In affected versions an attacker can access an Armeria server's local file system beyond its restricted directory by sending an HTTP request whose path contains `%2F` (encoded `/`), such as `/files/..%2Fsecrets.txt`, bypassing Armeria's path validation logic. Armeria 1.13.4 or above contains the hardened path validation logic that handles `%2F` properly. This vulnerability can be worked around by inserting a decorator that performs an additional validation on the request path.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2021-43795?

2 open source packages ship an affected version, including com.linecorp.armeria:armeria. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `com.linecorp.armeria:armeria` | Maven | From 1.12.0 | 1.13.4 |
| `com.linecorp.armeria:armeria` | Maven | From 1.12.0 | 1.13.4 |

Products: Linecorp Armeria.

## How do I fix CVE-2021-43795?

Upgrade com.linecorp.armeria:armeria to 1.13.4 or later.

## Is CVE-2021-43795 being exploited?

There is no known exploitation of CVE-2021-43795 in the wild and no public exploit code.

## Other vulnerabilities in line armeria

- [CVE-2024-1735](https://insights.sbomify.com/CVE-2024-1735/): Armeria SAML authentication bypass due to missing validation on unsigned SAML messages (critical 9.1)
- [CVE-2023-38493](https://insights.sbomify.com/CVE-2023-38493/): Paths contain matrix variables bypass decorators (high 7.5)
- [CVE-2019-16771](https://insights.sbomify.com/CVE-2019-16771/): Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response Splitting') in Armeria (medium 4.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-43795 and fix it if it is affected.

What it is: CVE-2021-43795 is a high-severity path traversal vulnerability in line armeria, published on 2 Dec 2021. 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-2021-43795 in the wild and no public exploit code.

Affected packages and fixed versions:
- com.linecorp.armeria:armeria (Maven): affected from 1.12.0; fixed in 1.13.4
- com.linecorp.armeria:armeria (Maven): affected from 1.12.0; fixed in 1.13.4

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-2021-43795/ (Markdown: https://insights.sbomify.com/CVE-2021-43795/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-43795
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-43795
- OSV: https://osv.dev/vulnerability/CVE-2021-43795

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-43795/
Summaries are generated and may contain mistakes; the official description above is the record.