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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-50285
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-17 20:16:50 UTC
Updated2026-09-24 21:25:27 UTC
DescriptionPomerium 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

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

EPSS: 0.007410000 probability, percentile 0.526920000 (date 2026-09-25)

Problem Types: CWE-770 | CWE-1284 | CWE-1284 CWE-1284: Improper Validation of Specified Quantity in Input | CWE-770 CWE-770: Allocation of Resources Without Limits or Throttling

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Pomerium Pomerium affected < 0.32.8 Not specified

References

ReferenceSourceLinkTags
github.com/pomerium/pomerium/releases/tag/v0.32.8 [email protected] github.com
github.com/pomerium/pomerium/commit/593eb81c7e5bdbe6071a30d330f374967869... [email protected] github.com
github.com/pomerium/pomerium/security/advisories/GHSA-ggw3-5987-rx77 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
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