# CVE-2026-73512: Envoy: use-after-free in QUIC on internal redirects

> An attacker can crash the Envoy proxy by sending HTTP/3 datagrams during internal redirects when Capsule Protocol is enabled.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 21 Sep 2026
- **Updated:** 22 Sep 2026
- **Also known as:** BIT-envoy-2026-73512, GHSA-r6j2-mrm5-72mg, MINI-923w-8g5r-5qw3, MINI-h8rh-gm8r-gjgc, MINI-hr6m-jmqh-q3xq, MINI-rxw4-3m3w-89cv

## What is CVE-2026-73512?

CVE-2026-73512 is a high-severity use after free vulnerability in Envoyproxy Envoy, published on 21 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy's HttpDatagramHandler caches the current RequestDecoder when Capsule Protocol is enabled. Stream recreation, including an internal redirect, replaces the ActiveStream and updates EnvoyQuicServerStream but does not update the handler's cached pointer. A subsequent HTTP/3 datagram can call decodeData through the freed decoder, causing invalid virtual dispatch and a process crash. The relevant scope boundary is that hTTP/3 datagrams and Capsule Protocol must be enabled, and the request must enter a stream-recreation path such as an internal redirect. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-73512?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `envoy` | Bitnami | All versions | 1.36.10, 1.37.6, 1.38.4, 1.39.1 |

Products: Envoyproxy Envoy.

## How do I fix CVE-2026-73512?

Upgrade envoy to a fixed version for your release line: 1.36.10, 1.37.6, 1.38.4 or 1.39.1.

## Is CVE-2026-73512 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-73512 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-2026-73512 and fix it if it is affected.

What it is: CVE-2026-73512 is a high-severity use after free vulnerability in Envoyproxy Envoy, published on 21 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-73512 exists.

Affected packages and fixed versions:
- envoy (Bitnami): affected all versions; fixed in 1.36.10, 1.37.6, 1.38.4, 1.39.1

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-2026-73512/ (Markdown: https://insights.sbomify.com/CVE-2026-73512/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-73512
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-73512
- OSV: https://osv.dev/vulnerability/CVE-2026-73512

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-73512/
Summaries are generated and may contain mistakes; the official description above is the record.