Summary
Credit
The go-git maintainers thank @kq5y for finding and reporting this issue privately to the go-git project.
Impact
A vulnerability has been identified in which a maliciously crafted .idx file can cause asymmetric memory consumption, potentially exhausting available memory and resulting in a Denial of Service (DoS) condition.
Exploitation requires write access to the local repository's .git directory, it order to create or alter existing .idx files.
The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.
CVE-2026-34165 has a CVSS score of 5.0 (Medium). The vector is requires local access, low privileges required, and user interaction required. 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 (5.17.1); 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
Users should upgrade to v5.17.1, or the latest v6 pseudo-version, in order to mitigate this vulnerability.
Frequently Asked Questions
- What is CVE-2026-34165? CVE-2026-34165 is a medium-severity allocation of resources without limits or throttling vulnerability in github.com/go-git/go-git/v5 (go), affecting versions >= 5.0.0, <= 5.17.0. It is fixed in 5.17.1. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
- How severe is CVE-2026-34165? CVE-2026-34165 has a CVSS score of 5.0 (Medium). 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/go-git/go-git/v5 are affected by CVE-2026-34165? github.com/go-git/go-git/v5 (go) versions >= 5.0.0, <= 5.17.0 is affected.
- Is there a fix for CVE-2026-34165? Yes. CVE-2026-34165 is fixed in 5.17.1. Upgrade to this version or later.
- Is CVE-2026-34165 exploitable, and should I be worried? Whether CVE-2026-34165 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-2026-34165 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-2026-34165? Upgrade
github.com/go-git/go-git/v5to 5.17.1 or later.