CVE-2020-8244: Remote Memory Exposure in bl
Summary
CVE-2020-8244: Remote Memory Exposure in bl. Affects bl across 4 version ranges.
< 1.2.3
>= 2.0.0, < 2.2.1
>= 3.0.0, < 3.0.1
>= 4.0.0, < 4.0.3
Fixed in 4 releases; the minimum fixed version depends on the release line you run. How to fix ↓
Also tracked for
- node-bl · Debian:11
The same CVE-2020-8244 is tracked separately for each ecosystem and vendor. Its fix information is the same; the package and affected versions differ.
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Background
The 'bl' package is an npm package that provides a BufferList class for managing buffers in a list-like structure. It is commonly used in Node.js applications for handling streams and buffers efficiently. However, versions prior to 4.0.3, 3.0.1, 2.2.1, and 1.2.3 are vulnerable to a buffer over-read vulnerability. This vulnerability can be exploited by an attacker to supply user input that, if it ends up in the 'consume()' argument and can become negative, can corrupt the BufferList state and expose uninitialized memory via regular '.slice()' calls.
Vulnerability Detail
The vulnerability in the 'bl' package allows an attacker to manipulate user input to corrupt the BufferList state and expose uninitialized memory. By supplying specific input that can result in a negative value in the 'consume()' argument, the attacker can trick the package into exposing sensitive information. This can lead to potential information disclosure and other security issues. The vulnerability has a CVSS score of 6.5, indicating a moderate severity level.
How To Fix
Latest published version: 7.0.13 as of 22 Oct 2026
npm install bl@7.0.13Upgrading to it may include breaking changes; the versions below are the minimum fixed release for this vulnerability.
If you can't move to the latest
The minimum fixed version depends on the release line you run.
-
< 1.2.31.2.3npm install bl@1.2.3 -
>= 2.0.0, < 2.2.12.2.1npm install bl@2.2.1 -
>= 3.0.0, < 3.0.13.0.1npm install bl@3.0.1 -
>= 4.0.0, < 4.0.34.0.3npm install bl@4.0.3
Tip — Not sure which release line you're on? Vulert can find the fix for the version you are using. Scan free →
Workaround
There is no specific workaround mentioned for this vulnerability. It is advised to update the package to the fixed versions as mentioned above.
Conclusion
The 'bl' package versions prior to 4.0.3, 3.0.1, 2.2.1, and 1.2.3 are vulnerable to a buffer over-read vulnerability that can lead to the exposure of uninitialized memory. To mitigate this vulnerability, it is recommended to update the package to the fixed versions. For further support on vulnerability remediation, you can reach out to DevNack.com.
See every vulnerability recorded for bl →
FAQ
This vulnerability can lead to the exposure of uninitialized memory, potentially allowing an attacker to access sensitive information.
You can use the Vulert Playground at Vulert Scanner to check if your application is affected by this vulnerability. Simply provide your package-lock.json file to the playground and it will alert you in real-time if the vulnerability is present.
There is no known exploit available for this vulnerability at the moment. However, it is still important to update the 'bl' package to the fixed versions to prevent any potential exploitation.
The only effective mitigation for this vulnerability is to update the 'bl' package to the fixed versions. It is recommended to regularly update your dependencies to ensure you are using the latest secure versions.
Yes, this vulnerability can be exploited remotely if an attacker is able to manipulate user input that ends up in the 'consume()' argument of the 'bl' package.
References
Related vulnerabilities
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