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CVE-2026-19931— Negotiate ambient user conn reuse

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是瑞典curl团队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 7.64.1版本至8.21.0版本存在会话机制问题漏洞，该漏洞源于libcurl在使用空凭据发起初始请求时，错误重用了为特定主机名建立的、使用Negotiate认证的HTTP连接，可能导致用户B的请求通过用户A先前已认证的连接发送。

AI Predicted 4.5 Difficulty: Hard EPSS 1.16% · P65

Possible ATT&CK Techniques 1 AI

T1003.001 · LSASS Memory

Affected Version Matrix 71

VendorProduct Version RangeStatus
curl curl 7.64.1< 8.14.2 affected
8.15.0< 8.16.1 affected
8.17.0< 8.20.1 affected
8.21.0< 8.22.0 affected
6c6035532383e300c712e4c1cd9fdd749ed5cf59< 7103a93b05bc69ea98ed9d05d02fa9eeba533f2f affected
8.21.0 affected
8.20.0 affected
8.19.0 affected
… +63 more rows
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I. Basic Information for CVE-2026-19931

Vulnerability Information
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Vulnerability Title
Negotiate ambient user conn reuse
Source: CVE Program / CVE List V5
Vulnerability Description
A flaw in libcurl makes it wrongly reuse an HTTP connection setup for a given hostname using Negotiate authentication, when the initial request is done using empty credentials. This can make user B's request get sent over user A's previously authenticated connection.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
对错误会话暴露数据元素
Source: CVE Program / CVE List V5
Vulnerability Title
curl 会话机制问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
curl是瑞典curl团队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 7.64.1版本至8.21.0版本存在会话机制问题漏洞，该漏洞源于libcurl在使用空凭据发起初始请求时，错误重用了为特定主机名建立的、使用Negotiate认证的HTTP连接，可能导致用户B的请求通过用户A先前已认证的连接发送。
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 7.64.1 ~ 8.14.2 -
curl curl 6c6035532383e300c712e4c1cd9fdd749ed5cf59 ~ 7103a93b05bc69ea98ed9d05d02fa9eeba533f2f -
curl curl 8.21.0 -

II. Public POCs for CVE-2026-19931

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III. Intelligence Information for CVE-2026-19931

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Vendor Advisories for CVE-2026-19931 (2)

Vendor Pages for CVE-2026-19931 (1)

Same Patch Batch · curl · 2026-09-06 · 9 CVEs total

CVE-2026-82208 wolfSSL CA-cache hit overrides callback
CVE-2026-82209 domain-scoped PSL domain cookie
CVE-2026-18924 HTTP/2 server push UAF
CVE-2026-80231 native CA store conn reuse
CVE-2026-80229 OpenSSL provider use-after-free
CVE-2026-80230 OpenSSL pinning bypass
CVE-2026-80255 secure cookie attribute bypass with tab
CVE-2026-13608 OpenLDAP SASL authentication bypass

IV. Related Vulnerabilities

Same product: curl
Same vendor: curl
Same weakness: CWE-488

V. Comments for CVE-2026-19931

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