postgres-protocol: Unbounded SCRAM iteration count allows a malicious server to cause CPU-exhaustion denial of service

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.7 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N · score source

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

A malicious, compromised, or man-in-the-middle server can supply an arbitrarily large SCRAM-SHA-256 PBKDF2 iteration count during authentication. The client runs it inline with no upper bound, pinning a tokio worker thread for minutes per connection, possibly stalling the whole async runtime. Applications that connect only to a trusted database are not exposed; the risk applies to clients that may connect to untrusted or user-supplied servers, or whose connection can be intercepted by a man-in-the-middle.

Published by the source

24 Aug 2026, 19:43 UTC

Last modified by the source

10 Sep 2026, 03:51 UTC

Source last checked

26 Oct 2026, 15:43 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-5x78-73v4-xg6w

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-5x78-73v4-xg6w

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: GHSA-5x78-73v4-xg6w

Advisory: postgres-protocol: Unbounded SCRAM iteration count allows a malicious server to cause CPU-exhaustion denial of service
IDs: GHSA-5x78-73v4-xg6w
Record: https://patchnext.com/advisories/ghsa-5x78-73v4-xg6w (revision 3, source checked 26 Oct 2026, 15:43 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: postgres-protocol 0.6.12. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io postgres-protocol: affected >= 0.3.0, < 0.6.12; fixed in 0.6.12

## Suggested inspection (read-only)
- crates.io postgres-protocol: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on postgres-protocol.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-5x78-73v4-xg6w (OSV record GHSA-5x78-73v4-xg6w lists affected ranges: crates.io postgres-protocol >=0.3.0 <0.6.12 (fixed))
- Verified: https://github.com/advisories/GHSA-5x78-73v4-xg6w (GitHub-reviewed advisory GHSA-5x78-73v4-xg6w lists affected ranges: crates.io postgres-protocol >=0.3.0 <0.6.12)

Commands are suggestions: review each one before running it.