PatchTheCVECVE-2026-121971: The component ScopingHttpClient in Symfony HttpClient merges the options of its default scope (such as auth_be
CVE-2026-121971 is a high-severity flaw (CVSS 8.2) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
The component ScopingHttpClient in Symfony HttpClient merges the options of its default scope (such as auth_bearer or auth_basic) into a request before resolving a relative URL against the base_uri, allowing a network-path reference such as "//evil.example/steal" to be sent to another origin together with the default scope’s credentials, and resulting in potential disclosure of those credentials to an attacker-controlled server. This affects Symf
Why this priority
- High severity
- Remotely exploitable, no login, no user action
No fix is published yet: follow the downgrade or mitigation steps.
Last updated 2026-11-04 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Timeline
- Published CVE record published
- Updated Record last modified
Advisories and coverage
Research and news
- VulDB Recent Entries: CVE-2026-121971 | Sensiolabs Symfony up to 5.4.55/6.4.49/7.4.22/8.1.10 ScopingHttpClient createForBaseUri information disclosure 2026-11-04
- Vulners Bulletins: CVE-2026-121971 2026-11-04
- Vulners Bulletins: CVE-2026-121971 Symfony: ScopingHttpClient Sends the Credentials of Its Default Scope to Other Origins Through Network-Path References 2026-11-04
- Vulners Bulletins: CVE-2026-121971 Symfony: ScopingHttpClient Sends the Credentials of Its Default Scope to Other Origins Through Network-Path References 2026-11-04
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-121971?
No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.
Is CVE-2026-121971 being exploited?
CVE-2026-121971 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-121971 affect?
CVE-2026-121971 affects affected software. Severity is high (CVSS 8.2). The component ScopingHttpClient in Symfony HttpClient merges the options of its default scope (such as auth_bearer or auth_basic) into a request before resolving a relative URL against the base_uri, allowing a network-path reference such as
How urgent is CVE-2026-121971?
Priority 34/100. High severity; Remotely exploitable, no login, no user action