CVE-2024-39315 is a medium-severity (CVSS 5.7) CWE-201 vulnerability in github.com/pomerium/pomerium. A fix is available for github.com/pomerium/pomerium — see the affected versions and patch details below.
Pomerium exposed OAuth2 access and ID tokens in user info endpoint response
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-39315.
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.
How urgent is this, really
CVE-2024-39315 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
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 | 0.26.1go get github.com/pomerium/pomerium@v0.26.1 |
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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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 CVE-2024-39315 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2024-39315 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2024-39315. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2024-39315 in your dependencies?
O3 Security finds CVE-2024-39315 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.