CVE-2025-65637: logrus DoS — Exploit & Fix

Description

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.

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CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-400 Uncontrolled Resource Consumption

Affected Products

Vendor	Product	Versions
turbopuffer	logrus	< 1.8.3
turbopuffer	logrus	All
turbopuffer	logrus	All

References

Advisories & Patches

https://github.com/sirupsen/logrus/issues/1370 https://github.com/sirupsen/logrus/pull/1376

Exploits

https://github.com/mjuanxd/logrus-dos-poc https://github.com/mjuanxd/logrus-dos-poc/blob/main/README.md https://github.com/sirupsen/logrus/issues/1370 https://security.snyk.io/vuln/SNYK-GOLANG-GITHUBCOMSIRUPSENLOGRUS-5564391

Other References

https://github.com/sirupsen/logrus/releases/tag/v1.8.3 https://github.com/sirupsen/logrus/releases/tag/v1.9.1 https://github.com/sirupsen/logrus/releases/tag/v1.9.3

Frequently Asked Questions

What is CVE-2025-65637? +

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. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2025-65637? +

CVE-2025-65637 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2025-65637? +

CVE-2025-65637 affects products from turbopuffer, specifically: logrus. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-65637? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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