CVE-2023-31136 is a low-severity (CVSS 3.7) CWE-522 vulnerability in github.com/vapor/postgres-nio. A fix is available for github.com/vapor/postgres-nio — see the affected versions and patch details below.
PostgresNIO processes unencrypted bytes from man-in-the-middle
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-31136.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
github.com/vapor/postgres-nioReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects SwiftURL packages — download data is not available via public APIs for these ecosystems.
Description
Impact
Any user of PostgresNIO connecting to servers with TLS enabled is vulnerable to a man-in-the-middle attacker injecting false responses to the client's first few queries, despite the use of TLS certificate verification and encryption.
The remaining text in this section is quoted verbatim from PostgreSQL's CVE-2021-23222 advisory:
If more preconditions hold, the attacker can exfiltrate the client's password or other confidential data that might be transmitted early in a session. The attacker must have a way to trick the client's intended server into making the confidential data accessible to the attacker. A known implementation having that property is a PostgreSQL configuration vulnerable to CVE-2021-23214. As with any exploitation of CVE-2021-23214, the server must be using trust authentication with a clientcert requirement or using cert authentication. To disclose a password, the client must be in possession of a password, which is atypical when using an authentication configuration vulnerable to CVE-2021-23214. The attacker must have some other way to access the server to retrieve the exfiltrated data (a valid, unprivileged login account would be sufficient).
Patches
The vulnerability is addressed in PostgresNIO versions starting from 1.14.2 via 2df54bc94607f44584ae6ffa74e3cd754fffafc7, which required additional support from SwiftNIO.
Workarounds
There are no known workarounds for unpatched users.
Additional Credits
Special thanks to PostgreSQL's Tom Lane <[email protected]> for reporting this issue!
References
- PostgreSQL security advisory for CVE-2021-23222
- GitHub security advisory GHSA-735f-7qx4-jqq5 for CVE-2021-23222
- PostgreSQL security advisory for CVE-2021-23214
- GitHub security advisory GHSA-467w-rrqc-395f for CVE-2021-23214
- SwiftNIO PR #2419 Add unprocessedBytes property on NIOSingleStepByteToMessageProcessor
- PostgresNIO commit 2df54bc94607f44584ae6ffa74e3cd754fffafc7
- PostgresNIO 1.42.2 release
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦SwiftURL | github.com/vapor/postgres-nio | all versions | 1.14.2 |
Affected Products
postgresniovaporDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/vapor/postgres-nio, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/vapor/postgres-nio to 1.14.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-31136 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2023-31136 in your dependencies?
Find it across SwiftURL, including transitive dependencies.