Is CVE-2026-39806 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-39806 being exploited in the wild.

How severe is CVE-2026-39806?

High severity, with a CVSS score of 7.5, published 13 May 2026.

Which products and versions are affected?

Mat Trudel Bandit >= 1.6.0, < 1.11.1, from 1.6.1 before 1.11.1.

Is there a fix for CVE-2026-39806?

A patch was published on 2026-05-13: Fixed in version 1.11.1 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-39806 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-39806?

Check whether you run Mat Trudel Bandit at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-39806: mtrudel bandit infinite loop in HTTP/1 chunked decoder

Q: Is there a fix for CVE-2026-39806?

A patch was published on 2026-05-13: Fixed in version 1.11.1 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Q: How is CVE-2026-39806 attacked?

It is attacked over the network, in a software library.

Q: Am I affected by CVE-2026-39806?

Check whether you run Mat Trudel Bandit at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-39806 · Severity: high · CVSS 7.5 · Published 2026-05-13

Bandit is an Elixir-based web server used to handle HTTP traffic for applications like Phoenix and Plug. A flaw in how it processes certain types of data transfers (chunked encoding) allows an unauthenticated attacker to crash or freeze the server. By sending a small number of specially crafted requests, an attacker can exhaust the server's resources, making the application unavailable to legitimate users.

Technologies: Mat Trudel Bandit. Vendors: Mat Trudel.

Quick answers

Is CVE-2026-39806 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-39806 being exploited in the wild.
How severe is CVE-2026-39806?: High severity, with a CVSS score of 7.5, published 13 May 2026.
Which products and versions are affected?: Mat Trudel Bandit >= 1.6.0, < 1.11.1, from 1.6.1 before 1.11.1.
Is there a fix for CVE-2026-39806?: A patch was published on 2026-05-13: Fixed in version 1.11.1 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-39806 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-39806?: Check whether you run Mat Trudel Bandit at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A vulnerability exists in 'Elixir.Bandit.HTTP1.Socket':do_read_chunked_data!/5 within lib/bandit/http1/socket.ex. The decoder fails to correctly handle RFC 9112-compliant chunked requests that include trailer fields. When a trailer is present after the last-chunk marker (0\r\n), the socket's match clauses fail to terminate, causing the code to compute a negative byte count and enter an infinite tail-recursion loop. This pins the worker process for the duration of the TCP connection. An attacker can exhaust the entire worker pool with a small number of concurrent connections, rendering the server unresponsive. The issue is fixed in version 1.11.1.

Affected products

mtrudel bandit from 1.6.1 before 1.11.1

Identifiers

CVE-2026-39806
GHSA-rf5q-vwxw-gmrf

Timeline

2026-05-13: disclosed
2026-05-13: patched: Fixed in version 1.11.1
2026-05-13: advisory

References

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