EUVD-2026-42884
GHSA-pj32-crq8-r292
Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Network-accessible endpoint requires no privileges or interaction; impact is limited to low integrity (ghost accounts) and low availability (invite exhaustion), no confidentiality loss.
Primary rating from Vendor (VulnCheck).
CVSS VectorVendor: VulnCheck
Lifecycle Timeline
2DescriptionCVE.org
Capgo before 12.128.2 contains an improper validation vulnerability in the accept_invitation endpoint that creates user accounts before captcha validation is enforced. Attackers can bypass captcha protection by sending POST requests with invalid captcha tokens to create unwanted accounts and burn invite links.
AnalysisAI
Capgo's accept_invitation endpoint creates user accounts before captcha validation is enforced, allowing unauthenticated remote attackers to bypass captcha entirely by submitting POST requests with invalid captcha tokens. This logic-ordering flaw enables automated account creation and exhaustion of invite links against any Capgo instance running versions prior to 12.128.2. No public exploit has been identified at time of analysis, and this CVE does not appear in the CISA KEV catalog.
Technical ContextAI
Capgo is an open-source live update platform for Capacitor-based mobile applications, providing over-the-air update delivery infrastructure. The vulnerability is a logic sequencing flaw in the accept_invitation endpoint where the account provisioning step executes before the captcha verification step completes - a direct manifestation of CWE-287 (Improper Authentication). Because the captcha check is a post-creation gate rather than a pre-creation gate, supplying any invalid token still results in a committed account record. The CPE string cpe:2.3:a:capgo:capgo:*:*:*:*:*:*:*:* confirms all versions prior to 12.128.2 are affected. The CVSS 4.0 base vector (AV:N/AC:L/AT:N/PR:N/UI:N) confirms the endpoint is reachable without authentication over the network.
RemediationAI
Upgrade Capgo to version 12.128.2 or later, which corrects the execution order of captcha validation to occur before account creation in the accept_invitation endpoint, as documented in the vendor advisory at https://github.com/Cap-go/capgo/security/advisories/GHSA-whc5-fvr7-g5v3. If an immediate upgrade is not feasible, apply rate limiting on the accept_invitation endpoint to constrain automated abuse - note this does not remediate the root validation flaw but reduces the attacker's throughput for burning invite links. Additionally, consider invalidating and regenerating all pending invite tokens after patching, since previously issued tokens may have been partially enumerated or abused. Restricting the endpoint to known IP ranges where invitees are expected to originate provides a further compensating control with the trade-off of blocking legitimate remote users.
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Same weakness CWE-287 – Improper Authentication
View allSame technique Authentication Bypass
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External POC / Exploit Code
Leaving vuln.today