# CVE-2025-29785: quic-go Has Panic in Path Probe Loss Recovery Handling

> A malicious QUIC client can trigger a nil-pointer dereference in quic-go, causing a denial of service via crafted path probe acknowledgments.

- **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:** 2 Jun 2025
- **Updated:** 2 Jun 2025
- **Also known as:** DEBIAN-CVE-2025-29785, GHSA-j972-j939-p2v3, GO-2025-3735, UBUNTU-CVE-2025-29785

## What is CVE-2025-29785?

CVE-2025-29785 is a high-severity vulnerability in quic-go, published on 2 Jun 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

quic-go is an implementation of the QUIC protocol in Go. The loss recovery logic for path probe packets that was added in the v0.50.0 release can be used to trigger a nil-pointer dereference by a malicious QUIC client. In order to do so, the attacker first sends valid QUIC packets from different remote addresses (thereby triggering the newly added path validation logic: the server sends path probe packets), and then sending ACKs for packets received from the server specifically crafted to trigger the nil-pointer dereference. v0.50.1 contains a patch that fixes the vulnerability. This release contains a test that generates random sequences of sent packets (both regular and path probe packets), that was used to verify that the patch actually covers all corner cases. No known workarounds are available.

Weakness: CWE-248 (Uncaught Exception)

## Which versions are affected by CVE-2025-29785?

3 open source packages ship an affected version, including github.com/quic-go/quic-go.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/quic-go/quic-go` | Go | From 0.50.0 | 0.50.1 |
| `github.com/quic-go/quic-go` | Go | From 0.50.0 | 0.50.1 |
| `github.com/quic-go/quic-go` | Go | From 0.50.0 | 0.50.1 |

## How do I fix CVE-2025-29785?

Upgrade github.com/quic-go/quic-go to 0.50.1 or later.

## Is CVE-2025-29785 being exploited?

There is no known exploitation of CVE-2025-29785 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-29785 and fix it if it is affected.

What it is: CVE-2025-29785 is a high-severity vulnerability in quic-go, published on 2 Jun 2025. 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-2025-29785 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/quic-go/quic-go (Go): affected from 0.50.0; fixed in 0.50.1
- github.com/quic-go/quic-go (Go): affected from 0.50.0; fixed in 0.50.1
- github.com/quic-go/quic-go (Go): affected from 0.50.0; fixed in 0.50.1

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-2025-29785/ (Markdown: https://insights.sbomify.com/CVE-2025-29785/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-29785
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-29785
- OSV: https://osv.dev/vulnerability/CVE-2025-29785

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-29785/
Summaries are generated and may contain mistakes; the official description above is the record.