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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
Low
Partial data leak
Integrity
None
No data modification
Availability
None
No disruption
CVSS Vector v3.1
Weakness Type (CWE)
References 4
https://curl.se/docs/CVE-2026-3783.html
2499f714-1537-4658-8207-48ae4bb9eae9
https://curl.se/docs/CVE-2026-3783.json
2499f714-1537-4658-8207-48ae4bb9eae9
https://hackerone.com/reports/3583983
2499f714-1537-4658-8207-48ae4bb9eae9
http://www.openwall.com/lists/oss-security/2026/03/11/2
af854a3a-2127-422b-91ae-364da2661108