Summary
Workarounds
No.
References
This issue has been reported publicly, but without any context, in https://github.com/quic-go/quic-go/issues/4981.
Impact
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.
CVE-2025-29785 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.50.1); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
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.
Frequently Asked Questions
- What is CVE-2025-29785? CVE-2025-29785 is a high-severity security vulnerability in github.com/quic-go/quic-go (go), affecting versions >= 0.50.0, < 0.50.1. It is fixed in 0.50.1.
- How severe is CVE-2025-29785? CVE-2025-29785 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/quic-go/quic-go are affected by CVE-2025-29785? github.com/quic-go/quic-go (go) versions >= 0.50.0, < 0.50.1 is affected.
- Is there a fix for CVE-2025-29785? Yes. CVE-2025-29785 is fixed in 0.50.1. Upgrade to this version or later.
- Is CVE-2025-29785 exploitable, and should I be worried? Whether CVE-2025-29785 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-29785 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2025-29785? Upgrade
github.com/quic-go/quic-goto 0.50.1 or later.