GHSA-38cx-cq6f-5755
Suggest an improvement- Source
- https://github.com/advisories/GHSA-38cx-cq6f-5755
- Import Source
- https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-38cx-cq6f-5755/GHSA-38cx-cq6f-5755.json
- JSON Data
- https://api.osv.dev/v1/vulns/GHSA-38cx-cq6f-5755
- Aliases
- Downstream
- Published
- 2026-06-15T17:31:28Z
- Modified
- 2026-09-10T03:51:07Z
- Severity
-
- 6.3 (Medium) CVSS_V4 - 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 CVSS Calculator
- Summary
- Symfony: IpUtils::PRIVATE_SUBNETS Omits IPv6 Transition Forms (6to4, NAT64, Teredo, IPv4-compatible): SSRF Bypass in NoPrivateNetworkHttpClient
- Details
-
Description
Symfony\Component\HttpClient\NoPrivateNetworkHttpClientis documented as a decorator that blocks requests to private networks by default. The list of blocked subnets (Symfony\Component\HttpFoundation\IpUtils::PRIVATE_SUBNETSon 6.4+, a private constant inNoPrivateNetworkHttpClienton 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 and64: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) orhttp://[2001::1]/(Teredo).IpUtils::isPrivateIp()returnsfalseandNoPrivateNetworkHttpClientdispatches 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::/96and64: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.
- Database specific
{ "cwe_ids": [ "CWE-184", "CWE-918" ], "github_reviewed": true, "github_reviewed_at": "2026-06-15T17:31:28Z", "nvd_published_at": null, "severity": "MODERATE" }- References
-
- https://github.com/symfony/symfony/security/advisories/GHSA-38cx-cq6f-5755
- https://github.com/symfony/symfony/commit/82765368cf74177c36613575182f168a2eb765b2
- https://github.com/symfony/symfony/commit/85b831555be8ea1f43bf01078afe87bc4c92f65e
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/http-client/CVE-2026-48736.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/http-foundation/CVE-2026-48736.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026-48736.yaml
- https://github.com/symfony/symfony
- https://symfony.com/cve-2026-48736
Affected packages
Packagist
symfony/http-client
Package
- Name
- symfony/http-client
- Purl
- pkg:composer/symfony/http-client
Affected versions
v5.*
symfony/http-foundation
Package
- Name
- symfony/http-foundation
- Purl
- pkg:composer/symfony/http-foundation
symfony/http-foundation
Package
- Name
- symfony/http-foundation
- Purl
- pkg:composer/symfony/http-foundation
Affected versions
v7.*
symfony/http-foundation
Package
- Name
- symfony/http-foundation
- Purl
- pkg:composer/symfony/http-foundation
symfony/symfony
Package
- Name
- symfony/symfony
- Purl
- pkg:composer/symfony/symfony
Affected versions
v5.*
symfony/symfony
Package
- Name
- symfony/symfony
- Purl
- pkg:composer/symfony/symfony
Affected versions
v6.*
symfony/symfony
Package
- Name
- symfony/symfony
- Purl
- pkg:composer/symfony/symfony
Affected versions
v7.*
symfony/symfony
Package
- Name
- symfony/symfony
- Purl
- pkg:composer/symfony/symfony