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CVE-2026-87861— cross-origin reuse of a Negotiate connection

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.

当使用环境用户凭据时,发往某一源的 HTTP 请求可能会被通过 Negotiate 协议为另一源预先认证的连接所发送,导致该请求原本应使用的凭据未被实际使用。

AI Predicted 8.1 Difficulty: Moderate EPSS 0.27% · P19

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 2

VendorProduct Version RangeStatus
curl curl 8.22.0≤ 8.22.0 affected
8.21.0≤ 8.21.0 affected
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I. Basic Information for CVE-2026-87861

Vulnerability Information

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Vulnerability Title
cross-origin reuse of a Negotiate connection
Source: CVE Program / CVE List V5
Vulnerability Description
When using ambient user credentials, an HTTP request directed to one origin may be dispatched over a connection previously authenticated via Negotiate for a different origin, leaving the request's intended credentials unused.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
curl curl 8.22.0 ~ 8.22.0 -

II. Public POCs for CVE-2026-87861

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III. Intelligence Information for CVE-2026-87861

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Vendor Pages for CVE-2026-87861 (2)

Other References for CVE-2026-87861 (1)

Same Patch Batch · curl · 2026-10-20 · 23 CVEs total

CVE-2026-92389 TFTP direction confusion
CVE-2026-107928 info leak uploading over WebSockets with GnuTLS
CVE-2026-107929 local interface connection reuse mixup
CVE-2026-94266 password leak in CURLINFO_EFFECTIVE_URL
CVE-2026-94265 Authorization: Negotiate sent to foreign origin
CVE-2026-86415 auto client cert connection reuse mixup
CVE-2026-86414 leaking host credentials to HTTP proxy
CVE-2026-92390 -J no-clobber guarantee bypassed with 103 early hints
CVE-2026-92387 never-ending loop via server response omission
CVE-2026-92388 FTP wildcard write callback mixup
CVE-2026-92386 server-set cookie aborts cookie jar load
CVE-2026-86409 stale SigV4 headers sent unintended
CVE-2026-92391 curl_mime_free stack overflow by recursion
CVE-2026-87865 knownhost callback mismatches key as missing
CVE-2026-87864 IMAP APPEND plus CRLF conversion command injection
CVE-2026-87863 HSTS response erases persisted entries
CVE-2026-87866 wolfSSL public-key pinning bypass
CVE-2026-87862 HSTS cache import drops longer-lived child
CVE-2026-86411 FTP connection reuse inherits client-certificate
CVE-2026-86412 server-set cookie erases cookie jar

Showing top 20 of 23 CVEs. View all on vendor page → →

IV. Related Vulnerabilities