curl HTTP Redirect Leaks OAuth2 Bearer Token
CVE-2026-3783 Published on March 11, 2026

token leak with redirect and netrc
When an OAuth2 bearer token is used for an HTTP(S) transfer, and that transfer performs a redirect to a second URL, curl could leak that token to the second hostname under some circumstances. If the hostname that the first request is redirected to has information in the used .netrc file, with either of the `machine` or `default` keywords, curl would pass on the bearer token set for the first host also to the second one.

NVD

Vulnerability Analysis

CVE-2026-3783 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. An automatable proof of concept (POC) exploit exists. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a small impact on integrity and availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
LOW
Integrity Impact:
NONE
Availability Impact:
NONE

Weakness Type

Insufficiently Protected Credentials

The product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval.


Products Associated with CVE-2026-3783

You can be notified by email with stack.watch whenever vulnerabilities like CVE-2026-3783 are published in these products:

Haxx Curl
 
Canonical Ubuntu Linux
 
Apple iOS
 
Apple iPadOS
 
Apple macOS
 
Apple Macos Sonoma
 
Apple tvOS
 
Apple watchOS
 
Red Hat Http Server
 

Affected Versions

curl: curl: curl:

Exploit Probability

EPSS
0.33%
Percentile
25.78%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.