Summary
Logrus is vulnerable to DoS when using Entry.Writer()
A denial-of-service vulnerability exists in github.com/sirupsen/logrus when using Entry.Writer() to log a single-line payload larger than 64KB without newline characters. Due to limitations in the internal bufio.Scanner, the read fails with "token too long" and the writer pipe is closed, leaving Writer() unusable and causing application unavailability (DoS). This affects versions < 1.8.3, 1.9.0, and 1.9.2. The issue is fixed in 1.8.3, 1.9.1, and 1.9.3+, where the input is chunked and the writer continues to function even if an error is logged.
Impact
Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.
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.
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github.com/sirupsen/logrus to 1.8.3 or later; github.com/sirupsen/logrus to 1.9.1 or later; github.com/sirupsen/logrus to 1.9.3 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2025-65637? CVE-2025-65637 is a high-severity uncontrolled resource consumption vulnerability in github.com/sirupsen/logrus (go), affecting versions < 1.8.3. It is fixed in 1.8.3, 1.9.1, 1.9.3. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
- Which versions of github.com/sirupsen/logrus are affected by CVE-2025-65637? github.com/sirupsen/logrus (go) versions < 1.8.3 is affected.
- Is there a fix for CVE-2025-65637? Yes. CVE-2025-65637 is fixed in 1.8.3, 1.9.1, 1.9.3. Upgrade to this version or later.
- Is CVE-2025-65637 exploitable, and should I be worried? Whether CVE-2025-65637 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-2025-65637 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-2025-65637?
- Upgrade
github.com/sirupsen/logrusto 1.8.3 or later - Upgrade
github.com/sirupsen/logrusto 1.9.1 or later - Upgrade
github.com/sirupsen/logrusto 1.9.3 or later
- Upgrade