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VulnerabilityPublished Updated

CVE-2026-6253: curl · Insufficiently Protected Credentials

Affects curlSource GCVE Database

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Not known to be exploited · CVSS 5.9 Medium.

Data as of 11 Nov 2026, 23:18 UTC

CVSS 3.1 base score
5.9Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CISA-ADPCVSS 3.15.9
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 13 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 11 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
curl curlAffected
  • =7.14.1
  • =8.15.0
  • =8.17.0
Fixed in–

AI-suggested

Until a fix is available, users should carefully review proxy configurations to avoid scenarios where different proxies with differing credential requirements are used for different URL schemes, especially when redirects are involved.

Description

CVE-2026-6253 is a vulnerability in curl where credentials intended for a first proxy may be mistakenly sent to a second proxy under certain redirect conditions. This occurs when curl is configured to use different proxies for different URL schemes, the first proxy requires credentials, the second proxy does not, and a redirect causes curl to switch proxies. The vulnerability has a medium severity rating with a CVSS score of 5.9.

References

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