Reference page — cumulative record through Sunday, October 4, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-6253

CVE-2026-6253MEDIUM

curl curl — proxy credentials leak over redirect-to proxy

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   H   N   N  U  N  N  H    5.9   .0075   53.4     —

AFFECTED
  Product  Versions                                    Fixed
  curl     7.14.1 –                                    —
  curl     3b60bb725913ce7339aefef0a14b12df4c24db60 –  —
  curl     8.19.0 –                                    —

TIMELINE
  Apr 13  Reserved by curl
  May 13  Published (CNA: curl)
  Sep 15  EXPLOIT PUBLISHED — CVE-2026-6253 (curl). Public exploit reference added.

CWE-522 · CNA: curl · CVSS v3.1 · 4 references · NVD status: Modified

Description

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

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
April 13, 2026	Reserved	Reserved by curl
May 13, 2026	Published	Published (CNA: curl)
September 15, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-6253 (curl). Public exploit reference added.

Affected

Affected products and packages — 3 rows
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
curl	curl	—	7.14.1	—
curl	curl	—	3b60bb725913ce7339aefef0a14b12df4c24db60	—
curl	curl	—	8.19.0	—

Weaknesses

CWE-522

References (4)

http://www.openwall.com/lists/oss-security/2026/04/29/11 [Mailing List, Patch, Third Party Advisory]
https://curl.se/docs/CVE-2026-6253.html [Patch, Vendor Advisory]
https://curl.se/docs/CVE-2026-6253.json [Vendor Advisory]
https://hackerone.com/reports/3669637 [Exploit, Issue Tracking, Third Party Advisory]

Authoritative record: CVE-2026-6253 at cve.org

Vendors: curl

Weaknesses: CWE-522

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-6253 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Sunday, October 4, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.