CVE-2026-56871: Panic in github.com/lib/pq Due to Malformed Backend Frame Length
Summary
CVE-2026-56871: Malformed backend frame length causes panic in github.com/lib/pq. Affects github.com/lib/pq versions >= 1.0.0. No fix is published. How to fix ↓
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Background
The github.com/lib/pq package is a pure Go Postgres driver that provides a way for Go applications to interact with PostgreSQL databases. It is widely used for its simplicity and efficiency in handling database connections and queries. However, it is vulnerable to a specific issue where it improperly handles backend frame lengths, leading to potential runtime panics.
Vulnerability Detail
The vulnerability arises from the package's trust in the unsigned 32-bit length of every PostgreSQL backend frame. When the length is between zero and three, the package subtracts four without verifying that the length is at least four. This results in a negative payload length, which causes the recvMessage function to slice the connection scratch buffer with a negative bound. Consequently, this leads to an unrecovered runtime panic that terminates the calling goroutine and the entire process, potentially disrupting application functionality.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, ensure that your application validates the backend frame lengths before processing them. This can be done by implementing checks to ensure that the length is greater than or equal to four before proceeding with any operations that rely on the frame length.
Conclusion
The CVE-2026-56871 vulnerability in the github.com/lib/pq package poses a significant risk due to its potential to cause runtime panics. It is crucial for developers using this package to update to the latest version to mitigate the risk. Additionally, implementing validation checks can serve as a temporary workaround while transitioning to the patched version.
See every vulnerability recorded for github.com/lib/pq →
FAQ
CVE-2026-56871 is a vulnerability in the github.com/lib/pq package that can cause a panic due to malformed backend frame lengths.
If your application uses the affected version of the github.com/lib/pq package, it may experience runtime panics, leading to crashes and disrupted functionality.
Yes, a patched version of the github.com/lib/pq package is available. Updating to the latest version will resolve the issue.
You can use Vulert, which monitors and alerts in real-time for open-source vulnerabilities in your software. It requires only the Gopkg.lock file for tracking.
Yes, you can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
References
Related vulnerabilities
Recent vulnerabilities recorded for github.com/lib/pq.
