vulnerability / NVI-00016051 / Revision 1
Pomerium Pre-Auth Memory Exhaustion via Unbounded zstd Decompression in HPKE Callback
GitHub lists this reviewed advisory for github.com/pomerium/pomerium. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
7.5 high
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
github.com/pomerium/pomerium
source listed>= 0.32.6, < 0.32.8
## Summary The HPKE V2 URL decode path in `pkg/hpke/url.go` decompresses attacker-controlled zstd data without any size limit. On Pomerium deployments using the stateless authentication flow (Pomerium Zero / hosted authenticate), the proxy's `/.pomerium/callback` endpoint is reachable without credentials and processes attacker-crafted HPKE-encrypted payloads before the sender's identity is validated. Because Pomerium's HPKE receiver public key is publicly served, an attacker can encrypt a decompression bomb, deliver it to the callback endpoint, and cause unbounded memory allocation — crashing or degrading the proxy process. ## Severity **High** (CVSS 3.1: 7.5) `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H` - **Attack Vector:** Network — the `/.pomerium/callback` route on the proxy service is externally reachable. - **Attack Complexity:** Low — the receiver public key is publicly available at `/.well-known/pomerium/hpke-public-key`; no special conditions apply. - **Privileges Required:** None — the callback endpoint is intentionally pre-authentication (it is the OAuth landing page). - **User Interaction:** None - **Scope:** Unchanged — the DoS is confined to the Pomerium proxy
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-ggw3-5987-rx77 ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.