CVE-2026-6253curl might erroneously pass on credentials for a first proxy to a second proxy.
Updated under an hour ago ()
Does this affect you?
It affects haxx curl. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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
- 5.9 MEDIUM (v3.1, NVD)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- CWE-522
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Not given
- NVD analysis
- Modified
- Record last updated
- Sep 15, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
haxx curl haxx:curl | from 7.14.1 before 8.20.0 | NVD |
References
- https://curl.se/docs/CVE-2026-6253.htmlpatch, vendor-advisory
- https://curl.se/docs/CVE-2026-6253.jsonvendor-advisory
- https://hackerone.com/reports/3669637exploit, issue-tracking, third-party-advisory
- http://www.openwall.com/lists/oss-security/2026/04/29/11mailing-list, patch, third-party-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.