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Servers and applications

CVE-2026-6253

curl might erroneously pass on credentials for a first proxy to a second proxy. This can happen when the following conditions are true: 1. curl is setup to use specific different proxies for different URL schemes 2. the first proxy needs credentials 3. the second proxy uses no credentials 4. while using the first proxy (using say `http://`), curl is asked to follow a redirect to a URL using…

Severity
Medium 5.9
Published
13 May 2026
Last changed
15 Sept 2026
Added to UpHeron
21 Oct 2026
Fixed in
8.20.0
Sources
NVD

Affected software

SoftwareAffected versions
curlServers and applications · cpe:a:haxx:curl
  • From 7.14.1 before 8.20.0

References

  • NVD https://nvd.nist.gov/vuln/detail/CVE-2026-6253
  • CVE.org https://www.cve.org/CVERecord?id=CVE-2026-6253