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Symfony: IpUtils::PRIVATE_SUBNETS Omits IPv6 Transition Forms (6to4, NAT64, Teredo, IPv4-compatible): SSRF Bypass in NoPrivateNetworkHttpClient

  • Publicada: 15.06.2026
  • Actualizado: 11.10.2026 10:22

Description

Symfony\Component\HttpClient\NoPrivateNetworkHttpClient is documented as a decorator that blocks requests to private networks by default. The list of blocked subnets (Symfony\Component\HttpFoundation\IpUtils::PRIVATE_SUBNETS on 6.4+, a private constant in NoPrivateNetworkHttpClient on 5.4) enumerates RFC1918, loopback, link-local and IPv4-mapped IPv6 (::ffff:0:0/96) prefixes, but omits the remaining IPv6 transition forms that can embed a private IPv4 destination: 6to4 (2002::/16, RFC 3056), Teredo (2001::/32, RFC 4380), NAT64 (64:ff9b::/96, RFC 6052 and 64:ff9b:1::/48, RFC 8215) and IPv4-compatible IPv6 (::/96, RFC 4291 §2.5.5.1).

IpUtils::checkIp6() is a pure bitwise CIDR comparison against the constants list and never extracts the embedded IPv4, so an attacker who can supply a URL writes the loopback / RFC1918 IPv4 target as e.g. http://[2002:7f00:1::]/ (6to4 → 127.0.0.1), http://[64:ff9b::7f00:1]/ (NAT64 → 127.0.0.1), http://[::7f00:1]/ (IPv4-compatible → 127.0.0.1) or http://[2001::1]/ (Teredo). IpUtils::isPrivateIp() returns false and NoPrivateNetworkHttpClient dispatches the request.

Real-world reachability of the embedded IPv4 depends on the deploy's IPv6 routing (6to4 tunnel interface, upstream NAT64 gateway, kernel handling of IPv4-compatible addresses), but the security boundary the decorator promises — the dispatch decision — is crossed regardless of whether the packet ultimately lands on the embedded IPv4.

Resolution

The private-subnet list now includes ::/96, 2002::/16, 2001::/32, 64:ff9b::/96 and 64:ff9b:1::/48. Blanket blocking of these prefixes matches the policy applied by Chromium and Mozilla's Private Network Access; server-side HTTPS APIs are not legitimately published on these prefixes.

The patches for this issue are available here for branch 5.4 and here for branch 6.4 (and forward-ported to 7.4, 8.0 and 8.1).

Credits

Symfony would like to thank tonghuaroot for reporting the issue and Nicolas Grekas for providing the fix.

Software afectado

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PlataformaPaqueteVersiones vulnerablesCorregida en
Paquete de Composer symfony/http-client >= 5.4.0, < 5.4.53 5.4.53
Paquete de Composer symfony/http-foundation >= 6.4.0, < 6.4.41, >= 7.0.0, < 7.4.13, >= 8.0.0, < 8.0.13 6.4.41, 7.4.13, 8.0.13
Paquete de Composer symfony/symfony >= 5.4.0, < 5.4.53, >= 6.4.0, < 6.4.41, >= 7.0.0, < 7.4.13, >= 8.0.0, < 8.0.13 5.4.53, 6.4.41, 7.4.13, 8.0.13

Referencias

Puntuación CVSS -
Vector CVSS
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
Debilidad (CWE)
CWE-184, CWE-918
Plataforma
Composer
Paquete
symfony/http-client, symfony/http-foundation, symfony/symfony
Publicada
15.06.2026
Actualizado
11.10.2026 10:22

Fuentes y licencias

OSV / GitHub Advisory Database - GHSA-38cx-cq6f-5755 - CC BY 4.0

Historial de vulnerabilidades: symfony/symfony

Todas las vulnerabilidades publicadas de este paquete (Paquete de Composer), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.

Todas (100) en el archivo
Entradas en total
100
Primera → última
11.2019 06.2026
Sin corrección
0
Explotada en ataques
0

Distribución por gravedad

  • Crítica 8
  • Alta 28
  • Media 51
  • Baja 13

Divulgaciones por año

Gravedad:
  1. Symfony: IpUtils::PRIVATE_SUBNETS Omits IPv6 Transition Forms (6to4, NAT64, Teredo, IPv4-compatible): SSRF Bypass in NoPrivateNetworkHttpClient esta entrada
    Media CVE-2026-48736 >= 5.4.0, < 5.4.53, >= 6.4.0, < 6.4.41, >= 7.0.0, < 7.4.13, >= 8.0.0, < 8.0.13 5.4.53, 6.4.41, 7.4.13, 8.0.13
  2. Symfony: Security Firewall Bypass via failure_forward Subrequest: Unauthenticated Access to access_control-Protected GET Routes
    Alta CVE-2026-48489 < 5.4.53, >= 6.0.0, < 6.4.41, >= 7.0.0, < 7.4.13, >= 8.0.0, < 8.0.13 5.4.53, 6.4.41, 7.4.13, 8.0.13
  3. Symfony has Unauthenticated PHP Object Deserialization in MonologBridge server:log Listener
    Alta CVE-2026-45077 < 5.4.52, >= 6.0.0, < 6.4.40, >= 7.0.0, < 7.4.12, >= 8.0.0, < 8.0.12 5.4.52, 6.4.40, 7.4.12, 8.0.12
  4. Symfony's HEAD Request Bypasses methods: ['GET'] Filter in #[IsGranted] / #[IsSignatureValid] / #[IsCsrfTokenValid]
    Alta CVE-2026-45075 >= 7.4.0, < 7.4.12, >= 8.0.0, < 8.0.12 7.4.12, 8.0.12
  5. Symfony has Email Header / SMTP Command Injection via CRLF in Symfony\Component\Mime\Address
    Alta CVE-2026-45067 < 5.4.52, >= 6.0.0, < 6.4.40, >= 7.0.0, < 7.4.12, >= 8.0.0, < 8.0.12 5.4.52, 6.4.40, 7.4.12, 8.0.12
  6. Symfony Vulnerable to Identity Spoofing via Unanchored DN Regex in X509Authenticator
    Alta CVE-2026-45063 < 5.4.52, >= 6.0.0-BETA1, < 6.4.40, >= 7.0.0-BETA1, < 7.4.12, >= 8.0.0-BETA1, < 8.0.12 5.4.52, 6.4.40, 7.4.12, 8.0.12
  7. Symfony's incorrect parsing of PATH_INFO can lead to limited authorization bypass
    Alta · 7.3 CVE-2025-64500 >= 2.0.0, < 5.4.50, >= 6.0.0, < 6.4.29, >= 7.0.0, < 7.3.7 5.4.50, 6.4.29, 7.3.7
  8. Symfony vulnerable to command execution hijack on Windows with Process class
    Alta · 8.4 CVE-2024-51736 < 5.4.46, >= 6.0.0, < 6.4.14, >= 7.0.0, < 7.1.7 5.4.46, 6.4.14, 7.1.7
  9. Symfony Cross-Site Request Forgery vulnerability in the Web Profiler
    Alta · 8.1 CVE-2014-6072 >= 2.0.0, < 2.3.19, >= 2.4.0, < 2.4.9, >= 2.5.0, < 2.5.4 2.3.19, 2.4.9, 2.5.4
  10. Symfony XML Entity Expansion security vulnerability
    Alta · 7.5 ghsa-q2gc-gg3x-7942 >= 2.0.0, < 2.0.17 2.0.17
  11. Symfony XML decoding attack vector through external entities
    Crítica · 9.8 ghsa-mmcv-fvq8-r9x3 >= 2.0.0, < 2.0.11 2.0.11
  12. Symfony allows direct access of ESI URLs behind a trusted proxy
    Alta · 7.5 CVE-2014-5245 >= 2.0.0, < 2.3.19, >= 2.4.0, < 2.4.9, >= 2.5.0, < 2.5.4 2.3.19, 2.4.9, 2.5.4
  13. Symfony vulnerable to denial of service via a malicious HTTP Host header
    Alta · 7.5 CVE-2014-5244 >= 2.0.0, < 2.3.19, >= 2.4.0, < 2.4.9, >= 2.5.0, < 2.5.4 2.3.19, 2.4.9, 2.5.4
  14. Code injection in the way Symfony implements translation caching in FrameworkBundle
    Alta · 7.5 CVE-2014-4931 >= 2.0.0, < 2.3.19, >= 2.4.0, < 2.4.9, >= 2.5.0, < 2.5.4 2.3.19, 2.4.9, 2.5.4
  15. Symfony Incorrect Access Control
    Crítica · 9.8 CVE-2017-11365 >= 2.7.30, < 2.7.32, >= 2.8.23, < 2.8.25, >= 3.2.10, < 3.2.12, >= 3.3.3, < 3.3.5 2.7.32, 2.8.25, 3.2.12, 3.3.5
  16. Symphony Denial of Service Via Overlong Usernames
    Alta · 7.5 CVE-2016-4423 >= 2.3.0, < 2.3.41, >= 2.4.0, < 2.7.13, >= 2.8.0, < 2.8.6, >= 3.0.0, < 3.0.6 2.3.41, 2.7.13, 2.8.6, 3.0.6
  17. Symfony Cryptographic Vulnerability
    Alta · 7.5 CVE-2016-1902 >= 2.3.0, < 2.3.37, >= 2.4.0, < 2.6.13, >= 2.7.0, < 2.7.9 2.3.37, 2.6.13, 2.7.9
  18. Symfony Vulnerable to Timing Attack
    Alta CVE-2015-8125 >= 2.3.0, < 2.3.35, >= 2.7.0, < 2.7.7, >= 2.4.0, < 2.6.12 2.3.35, 2.7.7, 2.6.12
  19. Symphony Vulnerable to PHP Code Injection via YAML Parsing
    Alta CVE-2013-1348 >= 2.0.0, < 2.0.22 2.0.22
  20. Symfony Arbitrary PHP code Execution
    Alta CVE-2013-1397 >= 2.2.0-BETA1, < 2.2.0-BETA2, >= 2.0.0, < 2.0.22, >= 2.1.0, < 2.1.7 2.2.0-BETA2, 2.0.22, 2.1.7
Mostrar más (17) Mostrando 20 de 37

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