# CVE-2023-35942: Envoy's gRPC access log crash caused by the listener draining

> A use-after-free vulnerability in Envoy's gRPC access logger causes a crash during listener draining, requiring specific configuration to exploit.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Jul 2023
- **Updated:** 24 Oct 2024
- **Also known as:** BIT-envoy-2023-35942, GHSA-69vr-g55c-v2v4

## What is CVE-2023-35942?

CVE-2023-35942 is a medium-severity use after free vulnerability in Envoyproxy Envoy, published on 25 Jul 2023. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12, gRPC access loggers using listener's global scope can cause a `use-after-free` crash when the listener is drained. Versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12 have a fix for this issue. As a workaround, disable gRPC access log or stop listener update.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2023-35942?

1 open source package ship an affected version, including envoy. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `envoy` | Bitnami | From 1.23.0 | 1.23.12, 1.24.10, 1.25.9, 1.26.4 |

Products: Envoyproxy Envoy.

## How do I fix CVE-2023-35942?

Upgrade envoy to a fixed version for your release line: 1.23.12, 1.24.10, 1.25.9 or 1.26.4.

## Is CVE-2023-35942 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-35942 exists.

## Other vulnerabilities in Envoyproxy Envoy

- [CVE-2022-29226](https://insights.sbomify.com/CVE-2022-29226/): Trivial authentication bypass in Envoy (critical 10.0)
- [CVE-2019-18801](https://insights.sbomify.com/CVE-2019-18801/): Memory corruption in n/a (critical 9.8)
- [CVE-2019-18802](https://insights.sbomify.com/CVE-2019-18802/): Security feature bypass in n/a (critical 9.8)
- [CVE-2020-35470](https://insights.sbomify.com/CVE-2020-35470/): Information disclosure in n/a (high 8.8)
- [CVE-2024-23324](https://insights.sbomify.com/CVE-2024-23324/): Envoy ext auth can be bypassed when Proxy protocol filter sets invalid UTF-8 metadata (high 8.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-35942 and fix it if it is affected.

What it is: CVE-2023-35942 is a medium-severity use after free vulnerability in Envoyproxy Envoy, published on 25 Jul 2023. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-35942 exists.

Affected packages and fixed versions:
- envoy (Bitnami): affected from 1.23.0; fixed in 1.23.12, 1.24.10, 1.25.9, 1.26.4

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-2023-35942/ (Markdown: https://insights.sbomify.com/CVE-2023-35942/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-35942
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-35942
- OSV: https://osv.dev/vulnerability/CVE-2023-35942

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-35942/
Summaries are generated and may contain mistakes; the official description above is the record.