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CVE-2026-6253— proxy credentials leak over redirect-to proxy

Quick assessment

Affected
curl curl
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

curl是cURL开源的一款用于从服务器传输数据或向服务器传输数据的工具。 curl存在安全漏洞，该漏洞源于代理凭证传递错误，可能导致第一个代理的凭证被错误传递给第二个代理。

AI Predicted 6.5 Difficulty: Moderate EPSS 0.75% · P53

Affected Version Matrix 161

VendorProduct Version RangeStatus
curl curl 7.14.1< 8.14.2 affected
8.15.0< 8.16.1 affected
8.17.0< 8.20.0 affected
3b60bb725913ce7339aefef0a14b12df4c24db60< 188c2f166a20fa97c2325b2da7d0e5cecc13725f affected
8.19.0 affected
8.18.0 affected
8.17.0 affected
8.16.0 affected
… +153 more rows
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I. Basic Information for CVE-2026-6253

Vulnerability Information
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Vulnerability Title
proxy credentials leak over redirect-to proxy
Source: CVE Program / CVE List V5
Vulnerability 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
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
不充分的凭证保护机制
Source: CVE Program / CVE List V5
Vulnerability Title
curl 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
curl是cURL开源的一款用于从服务器传输数据或向服务器传输数据的工具。 curl存在安全漏洞，该漏洞源于代理凭证传递错误，可能导致第一个代理的凭证被错误传递给第二个代理。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
curl curl 7.14.1 ~ 8.14.2 -
curl curl 3b60bb725913ce7339aefef0a14b12df4c24db60 ~ 188c2f166a20fa97c2325b2da7d0e5cecc13725f -
curl curl 8.19.0 -

II. Public POCs for CVE-2026-6253

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III. Intelligence Information for CVE-2026-6253

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Vendor Advisories for CVE-2026-6253 (3)

Same Patch Batch · curl · 2026-05-13 · 8 CVEs total

CVE-2026-7168 cross-proxy Digest auth state leak
CVE-2026-7009 OCSP stapling bypass with Apple SecTrust
CVE-2026-6429 netrc credential leak with reused proxy connection
CVE-2026-6276 stale custom cookie host causes cookie leak
CVE-2026-4873 connection reuse ignores TLS requirement
CVE-2026-5545 wrong reuse of HTTP Negotiate connection
CVE-2026-5773 wrong reuse of SMB connection

IV. Related Vulnerabilities

Same product: curl
Same vendor: curl
Same weakness: CWE-522

V. Comments for CVE-2026-6253

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