PoC Index

CVE-2026-55834

MEDIUM 4.3EPSS 0.3%

Pocket ID is an OIDC provider that allows users to authenticate with their passkeys to services. From 2.6.0 until 2.9.0, frontend/src/routes/authorize/+page.ts reads the redirect_uri query parameter and frontend/src/routes/authorize/+page.svelte uses the raw callbackURL in redirectWithError when prompt=none cannot complete silent authorization. The client-side path only blocks javascript and data schemes and does not invoke the backend callback allow-list validation, so an unauthenticated attacker who knows a valid client_id can redirect a victim browser to an arbitrary HTTP or HTTPS origin for phishing or OIDC error and state smuggling. This issue is fixed in version 2.9.0.

CVSS v3.1
4.3 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
CVSS v3.1
4.3 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
EPSS
0.27% chance of exploitation in the next 30 days, 19th percentile
Published
2026-08-28

Proof-of-concept exploits (1)

References

Related