Insufficiently Protected Credentials Affecting curl package, versions <8.18.0-1ubuntu2.1


Severity

Recommended
medium

Based on Ubuntu security rating.

Threat Intelligence

EPSS
0.03% (9th percentile)

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  • Snyk IDSNYK-UBUNTU2604-CURL-16335322
  • published4 May 2026
  • disclosed13 May 2026

Introduced: 4 May 2026

NewCVE-2026-6253  (opens in a new tab)
CWE-522  (opens in a new tab)

How to fix?

Upgrade Ubuntu:26.04 curl to version 8.18.0-1ubuntu2.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream curl package and not the curl package as distributed by Ubuntu. See How to fix? for Ubuntu:26.04 relevant fixed versions and status.

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 another scheme (say https://), accessed using a second, different, proxy

CVSS Base Scores

version 3.1