GHSA-rrqr-7w59-637v
MEDIUMPomerium exposed OAuth2 access and ID tokens in user info endpoint response
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
github.com/pomerium/pomeriumReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Impact
The Pomerium user info page (at /.pomerium) unintentionally included serialized OAuth2 access and ID tokens from the logged-in user's session. These tokens are not intended to be exposed to end users.
This issue may be more severe in the presence of an XSS vulnerability in an upstream application proxied through Pomerium. If an attacker could insert a malicious script onto a web page proxied through Pomerium, that script could access these tokens by making a request to the /.pomerium endpoint.
Upstream applications that authenticate only the ID token may be vulnerable to user impersonation using a token obtained in this manner.
Note that an OAuth2 access token or ID token by itself is not sufficient to hijack a user's Pomerium session. Upstream applications should not be vulnerable to user impersonation via these tokens provided:
- the application verifies the Pomerium JWT for each request,
- the connection between Pomerium and the application is secured by mTLS,
- or the connection between Pomerium and the application is otherwise secured at the network layer.
Patches
Patched in Pomerium v0.26.1.
Workarounds
None
For more information
If you have any questions or comments about this advisory:
- Open an issue in pomerium/pomerium
- Email us at [email protected]
Credit to Vadim Sheydaev, aka Enr1g for reporting this issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/pomerium/pomerium | all versions | 0.26.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/pomerium/pomerium. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/pomerium/pomerium to 0.26.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-rrqr-7w59-637v is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-rrqr-7w59-637v is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-rrqr-7w59-637v. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-rrqr-7w59-637v in your dependencies?
O3 detects GHSA-rrqr-7w59-637v across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.