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CVE-2026-123125— Symfony: Ip Constraint public/private Modes Accept IPv4-Mapped and IPv4-Compatible IPv6 Addresses allowing SSRF Filter Bypass

Quick assessment

Affected
sensiolabs symfony
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.

Symfony Validator 组件中的 在 约束的过滤模式下未能完整分类内部地址，导致部分内部地址被错误地识别为公网地址。该问题存在于以下版本中：Symfony 5.4.56 之前、6.x 系列 6.4.50 之前、7.x 系列 7.4.23 之前，以及 8.x 系列 8.1.11 之前，可能引发服务器端请求伪造（SSRF）漏洞。 在这些过滤模式下， 依赖 PHP 的 和 标志将地址分类为公网、私有或保留地址。然而，这些标志并未涵盖共享地址空间（100.64.0.0/10），也未覆盖 IPv4 映射、IPv4

CVSS 6.3 · Medium

Affected Version Matrix 4

VendorProduct Version RangeStatus
sensiolabs symfony < 5.4.56 affected
6.0.0< 6.4.50 affected
7.0.0< 7.4.23 affected
8.0.0< 8.1.11 affected
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I. Basic Information for CVE-2026-123125

Vulnerability Information
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Vulnerability Title
Symfony: Ip Constraint public/private Modes Accept IPv4-Mapped and IPv4-Compatible IPv6 Addresses allowing SSRF Filter Bypass
Source: CVE Program / CVE List V5
Vulnerability Description
The Symfony Validator component IpValidator incompletely classifies internal addresses in the filtered modes of the Ip constraint, so some internal addresses are accepted as public, which can lead to Server-Side Request Forgery (SSRF) in Symfony versions prior to 5.4.56, 6.x prior to 6.4.50, 7.x prior to 7.4.23, and 8.x prior to 8.1.11. In these modes, IpValidator relies on the PHP flags FILTER_FLAG_NO_PRIV_RANGE and FILTER_FLAG_NO_RES_RANGE to classify addresses as public, private, or reserved. These flags do not cover shared address space (100.64.0.0/10) or IPv4-mapped, IPv4-compatible, and 6to4 IPv6 addresses, which can embed internal IPv4 addresses. A value such as ::ffff:127.0.0.1 can therefore pass validation even though it points to an internal host. Applications that rely on the Ip constraint to reject internal addresses, for example before making a server-side request to a user-supplied address, can be exposed to SSRF.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
不完整的黑名单
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
sensiolabs symfony 0 ~ 5.4.56 -

II. Public POCs for CVE-2026-123125

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III. Intelligence Information for CVE-2026-123125

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Other References for CVE-2026-123125 (2)

Same Patch Batch · sensiolabs · 2026-11-05 · 4 CVEs total

CVE-2026-123119 2.3 LOW Symfony: NoPrivateNetworkHttpClient Does Not Pin the Checked IP of Cached Hosts, Letting D
CVE-2026-118517 2.3 LOW Symfony: HtmlSanitizer allowLinkHosts() / allowMediaHosts() Bypass via URLs Without a Well
CVE-2026-121949 2.3 LOW Symfony: HtmlSanitizer Does Not URL-Sanitize srcset and imagesrcset: Media Scheme and Host

IV. Related Vulnerabilities

Same product: symfony
Same vendor: sensiolabs
Same weakness: CWE-184