What’s Vulnerable › Vulnerabilities

CVE-2026-3783: token leak with redirect and netrc

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-03-11 · updated 2026-09-15
• Weakness: CWE-522

Description

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.

Affected products

• curl: from 7.33.0 before 8.19.0 — fixed in 8.19.0

How to fix

Upgrade to a fixed version: curl 8.19.0. Check the vendor advisory for mitigations.

References

• https://curl.se/docs/CVE-2026-3783.html
• https://curl.se/docs/CVE-2026-3783.json
• https://hackerone.com/reports/3583983
• http://www.openwall.com/lists/oss-security/2026/03/11/2

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