Summary
Bugsink is vulnerable to unauthenticated remote DoS via crafted Brotli input (via CPU)
Patched in Bugsink 2.0.6
References
The vulnerability in this security advisory is similar to, but distinct from, another brotli-related problem in Bugsink:
https://github.com/bugsink/bugsink/security/advisories/GHSA-fc2v-vcwj-269v
Impact
In affected versions, a specially crafted Brotli-compressed envelope can cause Bugsink to spend excessive CPU time in decompression, leading to denial of service.
This can be done if the DSN is known, which it is in many common setups (JavaScript, Mobile Apps).
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-2025-64509 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 (2.0.6); 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
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2025-64509? CVE-2025-64509 is a high-severity allocation of resources without limits or throttling vulnerability in bugsink (pip), affecting versions < 2.0.6. It is fixed in 2.0.6. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
- How severe is CVE-2025-64509? CVE-2025-64509 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 bugsink are affected by CVE-2025-64509? bugsink (pip) versions < 2.0.6 is affected.
- Is there a fix for CVE-2025-64509? Yes. CVE-2025-64509 is fixed in 2.0.6. Upgrade to this version or later.
- Is CVE-2025-64509 exploitable, and should I be worried? Whether CVE-2025-64509 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-2025-64509 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-2025-64509? Upgrade
bugsinkto 2.0.6 or later.