CVE-2024-39315: Pomerium is an identity and context-aware access proxy. Prior to version 0.26.1, the Pomerium user info page (at `/.pomerium`) unintentionally include...

Description

Pomerium is an identity and context-aware access proxy. Prior to version 0.26.1, 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 a cross-site scripting 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. The issue is patched in Pomerium v0.26.1. No known workarounds are available.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

EPSS Probability

0.42%

33.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-201

Affected Software

Vendor	Product	Versions
Pomerium	Pomerium	< 0.26.1

References

Timeline

Published: Jul 2, 2024
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2024-39315?

Pomerium is an identity and context-aware access proxy. Prior to version 0.26.1, 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 a cross-site scripting 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. The issue is patched in Pomerium v0.26.1. No known workarounds are available.

How severe is CVE-2024-39315?

CVE-2024-39315 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.42% probability of exploitation in the next 30 days.

How do I fix CVE-2024-39315?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.