Google::Auth versions before 0.09 for Perl allow server side request forgery and credential exfiltration via unvalidated URLs taken from the credentials JSON

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-66901
StatePUBLISHED
AssignerCPANSec
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-04 21:16:37 UTC
Updated2026-08-04 23:16:53 UTC
DescriptionGoogle::Auth versions before 0.09 for Perl allow server side request forgery and credential exfiltration via unvalidated URLs taken from the credentials JSON. The URLs the library requests are read from the credentials JSON, and their hosts were not checked against the universe domain before the request. For an external_account configuration, retrieve_subject_token fetched credential_source.url with headers from the same JSON, and fetch_access_token posted the subject token to token_url, then sent the STS access token it received to service_account_impersonation_url in an Authorization: Bearer header. The authorized_user, impersonated_service_account and service_account configurations posted the client secret and refresh token, the source access token, and a signed JWT assertion to their own JSON-supplied token_uri or impersonation URL. Any caller that builds credentials from a configuration it does not fully control issues those requests from the application's network position, reaching hosts the configuration names, including internal services and link-local metadata endpoints, and hands them the credentials each request carries. The service_account assertion is bound to aud, so it is not replayable against Google. Version 0.06 added a _validate_url host check to the external_account class, keyed on a universe_domain read from the same credentials JSON. Version 0.07 gated a JSON-supplied universe domain behind GOOGLE_EXTERNAL_ACCOUNT_ALLOW_CUSTOM_UNIVERSES=1, deriving the pin flag from arguments that an earlier BUILDARGS pass had already merged on the make_creds path. Version 0.08 passed the pin decision through as an explicit constructor argument and moved _validate_url to Google::Auth::Credentials, adding the call to UserRefreshCredentials and ImpersonatedServiceAccountCredentials, and 0.09 added it to ServiceAccountCredentials.

Risk And Classification

Problem Types: CWE-201 | CWE-918 | CWE-918 CWE-918 Server-Side Request Forgery (SSRF) | CWE-201 CWE-201 Insertion of Sensitive Information Into Sent Data

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA CJCOLLIER GoogleAuth affected 0.09 custom Not specified

References

ReferenceSourceLinkTags
github.com/GoogleCloudPlatform/google-auth-library-perl/commit/c95c77e70... 9b29abf9-4ab0-4765-b253-1875cd9b441e github.com
github.com/GoogleCloudPlatform/google-auth-library-perl/commit/cbbb07804... 9b29abf9-4ab0-4765-b253-1875cd9b441e github.com
metacpan.org/release/CJCOLLIER/Google-Auth-0.09/changes 9b29abf9-4ab0-4765-b253-1875cd9b441e metacpan.org
github.com/GoogleCloudPlatform/google-auth-library-perl/commit/cd42bdef5... 9b29abf9-4ab0-4765-b253-1875cd9b441e github.com
github.com/GoogleCloudPlatform/google-auth-library-perl/commit/9b5157062... 9b29abf9-4ab0-4765-b253-1875cd9b441e github.com
www.openwall.com/lists/oss-security/2026/08/04/34 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

SourceTimeEvent
CNA2026-07-28T00:00:00.000ZVersion 0.06 released with a partial fix.
CNA2026-08-02T00:00:00.000ZVersion 0.08 released, extending the fix to two further credential classes.
CNA2026-08-03T00:00:00.000ZVersion 0.09 released with the complete fix.

Solutions

CNA: Upgrade to Google-Auth 0.09 or later, which validates each URL host against googleapis.com or a universe domain pinned by the application before the request.

Workarounds

CNA: For deployments that cannot upgrade to 0.09, ensure that every credentials configuration reaching the Application Default Credentials flow comes from a trusted source.

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