Pomerium: Pre-Auth Memory Exhaustion via Unbounded zstd Decompression in HPKE Callback (CVE-2026-50285) | HOL Guard CVE

High severityCVE-2026-50285GHSA-GGW3-5987-RX77

Pomerium: Pre-Auth Memory Exhaustion via Unbounded zstd Decompression in HPKE Callback

Answer in brief

CVE-2026-50285 records a High severity vulnerability in Pomerium: Pre-Auth Memory Exhaustion via Unbounded zstd Decompression in HPKE Callback. The current sources do not mark it as known exploited. The current feed maps pomerium/pomerium (generic), github.com/pomerium/pomerium (go). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 17, 2026Updated Sep 17, 2026Source checked Sep 17, 2026First seen by HOL Jul 15, 2026Material review Sep 17, 2026

Upstream Advisory

Key facts

Risk: High
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps pomerium/pomerium (generic), github.com/pomerium/pomerium (go). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
pomerium/pomeriumgeneric	< 0.32.8	Not reported
github.com/pomerium/pomeriumgo	>=0.32.6,<0.32.8	0.32.8

Recommended response

Check inventory. Check lockfiles and deployed manifests for pomerium/pomerium, github.com/pomerium/pomerium.
Review the reported fix. Update github.com/pomerium/pomerium to 0.32.8 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Jul 15, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.