# CVE-2026-34183: Unbounded Memory Growth in the QUIC PATH_CHALLENGE Handler

> A remote attacker can cause a Denial of Service in OpenSSL QUIC implementations by flooding PATH_CHALLENGE frames, leading to unbounded memory growth and application termination.

- **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:** 9 Jun 2026
- **Updated:** 10 Jun 2026
- **Also known as:** ALPINE-CVE-2026-34183, AZL-89925, BELL-CVE-2026-34183, DEBIAN-CVE-2026-34183, GHSA-f5vx-f6jp-89j6, JLSEC-2026-1136, MINI-hw24-mf7w-9fwh, UBUNTU-CVE-2026-34183

## What is CVE-2026-34183?

CVE-2026-34183 is a high-severity denial of service vulnerability in Openssl Openssl, published on 9 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Issue summary: Remote peer may exhaust heap memory of the QUIC
server or client by flooding it with packets containing PATH_CHALLENGE
frames.

Impact summary: A malicious remote peer can cause an unbounded
memory allocation which can lead to an abnormal termination of the
application acting as a QUIC client or server and a Denial of Service.

A remote peer may exhaust heap memory by flooding the local
QUIC stack with PATH_CHALLENGE frames. The local QUIC stack
allocates a PATH_RESPONSE frame for every PATH_CHALLENGE it receives.
The allocated PATH_RESPONSE frame gets freed only when the remote
peer acknowledges reception of the PATH_RESPONSE frame which will
not be done by a malicious peer.

The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by
this issue. The QUIC stack is outside of OpenSSL FIPS module
boundary.

Weakness: CWE-1325 (Improperly Controlled Sequential Memory Allocation)

## Which versions are affected by CVE-2026-34183?

It affects 1 product.


Products: Openssl Openssl.

## How do I fix CVE-2026-34183?

Apply the vendor's patch.

## Is CVE-2026-34183 being exploited?

There is no known exploitation of CVE-2026-34183 in the wild and no public exploit code.

## Other vulnerabilities in Openssl Openssl

- [CVE-2009-3245](https://insights.sbomify.com/CVE-2009-3245/): Null dereference in n/a (critical 10.0)
- [CVE-2006-3738](https://insights.sbomify.com/CVE-2006-3738/): Memory corruption in n/a (critical 10.0)
- [CVE-2026-63073](https://insights.sbomify.com/CVE-2026-63073/): Untrusted Sender DN Used as Format String in CMP Response Validation (critical 9.8)
- [CVE-2016-6309](https://insights.sbomify.com/CVE-2016-6309/): Use after free in n/a (critical 9.8)
- [CVE-2016-0799](https://insights.sbomify.com/CVE-2016-0799/): Integer overflow in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34183 and fix it if it is affected.

What it is: CVE-2026-34183 is a high-severity denial of service vulnerability in Openssl Openssl, published on 9 Jun 2026. 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-2026-34183 in the wild and no public exploit code.

Affected product: Openssl Openssl. 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-2026-34183/ (Markdown: https://insights.sbomify.com/CVE-2026-34183/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34183
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34183
- OSV: https://osv.dev/vulnerability/CVE-2026-34183

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-34183/
Summaries are generated and may contain mistakes; the official description above is the record.