CVE-2026-3783

low-risk

Published 2026-03-11

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.

Do I need to act?

0.02% chance of exploitation

EPSS score — low exploit probability

Not on CISA KEV list

No confirmed active exploitation reported to CISA

Patch status unknown

Check vendor advisories for fix availability and mitigation guidance

CVSS 5.3/10 Medium

NETWORK / LOW complexity

Affected Products (1)

Curl

Affected Vendors

Haxx

References (4)

Patch https://curl.se/docs/CVE-2026-3783.html

Vendor Advisory https://curl.se/docs/CVE-2026-3783.json

Exploit https://hackerone.com/reports/3583983

Mailing List http://www.openwall.com/lists/oss-security/2026/03/11/2

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low-risk

Severity 21/34 · High

Exploitability 0/34 · Minimal

Exposure 5/34 · Minimal