---
id: "CVE-2026-107929"
kind: "vulnerability"
aliases: ["CVE-2026-107929"]
title: "curl: connection reuse ignores interface binding, sending traffic from wrong source"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["c", "curl", "libcurl", "package", "php", "python"]
not_affected_if: ["default-config"]
published_at: "2026-10-20T21:17:15+00:00"
first_seen_at: "2026-10-23T21:57:21+00:00"
updated_at: "2026-10-25T05:04:31+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-107929", "first_seen_at": "2026-10-23T21:57:21+00:00"}]
---

# curl: connection reuse ignores interface binding, sending traffic from wrong source

When curl is given an interface prefix such as if!, host! or ifhost! for CURLOPT_INTERFACE or --interface, that binding is left out of the connection reuse key. A later transfer requesting a different source can silently reuse an earlier connection and leave from the wrong source address.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- unknown

## Fix

- unknown

## Timeline

- 2026-10-23T21:57:21+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-107929

## From the sources

When `CURLOPT_INTERFACE` (or the command line tool's `--interface` option) is
set with one of the documented prefixes (`if!`, `host!`, `ifhost!`), that
binding is not part of the connection reuse key, so a later transfer asking
for a different source can silently reuse an existing connection and go out
from the earlier transfer's source address

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_