CVE-2026-50285

HighCVSS 7.5

Published: 17/09/2026(UTC)Updated: 24/09/2026(UTC)Translated: 18/09/2026(UTC)NVD NIST

Exploitation Probability (EPSS)

Elevated risk

0.74%

53th percentile - higher than 53% of all known CVEs

Summary

In Pomerium (an identity and context-aware access proxy) before version 0.32.8, decodeQueryStringV2 in pkg/hpke/url.go performs zstd decompression of attacker-controlled data without an output-memory limit when DecryptURLValues processes HPKE V2 values for Stateless.Callback. In hosted or stateless authentication deployments, an unauthenticated attacker can obtain the receiver key from /.well-known/pomerium/hpke-public-key, provide a matching attacker-controlled sender key, and send a compressed payload to /.pomerium/callback that expands before validateSenderPublicKey rejects the sender. The issue is fixed in version 0.32.8.

Risk Assessment

An unauthenticated attacker can allocate hundreds of megabytes per request, exhausting proxy memory, crashing or degrading the process, and blocking access to applications protected by the deployment. Stateful deployments are not affected.

Recommendation

Update Pomerium to version 0.32.8 or later. If not possible, consider restricting access to /.pomerium/callback and monitoring proxy memory usage.

Other vulnerabilities in Pomerium

CVE-2023-33189Critical
Pomerium, as an identity and context-aware access proxy, may make incorrect authorization decisions due to specially crafted requests. This issue has been patched in versions 0.17.4, 0.18.1, 0.19.2, 0.20.1, 0.21.4, and 0.22.2.

Original NVD description (English source)

Pomerium is an identity and context-aware access proxy. Prior to 0.32.8, decodeQueryStringV2 in pkg/hpke/url.go performs zstd decompression of attacker-controlled data without an output-memory limit when DecryptURLValues processes HPKE V2 values for Stateless.Callback in internal/authenticateflow/stateless.go. In hosted or stateless authentication deployments, an unauthenticated attacker can obtain the receiver key from /.well-known/pomerium/hpke-public-key, provide a matching attacker-controlled sender key, and send a compressed payload to /.pomerium/callback that expands before validateSenderPublicKey rejects the sender. This can allocate hundreds of megabytes per request, exhaust proxy memory, crash or degrade the process, and block access to applications protected by the deployment. Stateful deployments are not affected because the stateful callback verifies its HMAC signature before decryption and decompression. This issue is fixed in version 0.32.8.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS