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CVE-2026-33540— Distribution affected by pull-through cache credential exfiltration via www-authenticate bearer realm

Quick assessment

Affected
distribution distribution
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.

Distribution是Distribution开源的用于打包、运输、存储和交付内容的工具集。 Distribution 3.1.0之前版本存在安全漏洞，该漏洞源于拉取缓存模式下未验证领域URL，可能导致配置的上游凭据发送至攻击者控制的URL。

CVSS 7.5 · High EPSS 0.39% · P31
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I. Basic Information for CVE-2026-33540

Vulnerability Information
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Vulnerability Title
Distribution affected by pull-through cache credential exfiltration via www-authenticate bearer realm
Source: CVE Program / CVE List V5
Vulnerability Description
Distribution is a toolkit to pack, ship, store, and deliver container content. Prior to 3.1.0, in pull-through cache mode, distribution discovers token auth endpoints by parsing WWW-Authenticate challenges returned by the configured upstream registry. The realm URL from a bearer challenge is used without validating that it matches the upstream registry host. As a result, an attacker-controlled upstream (or an attacker with MitM position to the upstream) can cause distribution to send the configured upstream credentials via basic auth to an attacker-controlled realm URL. This vulnerability is fixed in 3.1.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
服务端请求伪造(SSRF)
Source: CVE Program / CVE List V5
Vulnerability Title
Distribution 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Distribution是Distribution开源的用于打包、运输、存储和交付内容的工具集。 Distribution 3.1.0之前版本存在安全漏洞，该漏洞源于拉取缓存模式下未验证领域URL，可能导致配置的上游凭据发送至攻击者控制的URL。
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
distribution distribution < 3.1.0 -

II. Public POCs for CVE-2026-33540

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III. Intelligence Information for CVE-2026-33540

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Vendor Advisories for CVE-2026-33540 (1)

IV. Related Vulnerabilities

Same product: distribution
Same vendor: distribution
Same weakness: CWE-918

V. Comments for CVE-2026-33540

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