CVE-2026-6665
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedThe SCRAM code in PgBouncer before 1.25.2 did not check the return value of strlcat() correctly when building the contents of the SCRAM client-final-message. A malicious backend that sends a SCRAM server-final-message with a long nonce can trigger a stack overflow.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidencePgBouncer's SCRAM authentication implementation fails to properly check the return value of strlcat() when constructing the SCRAM client-final-message. A malicious backend can send a specially crafted server-final-message containing an oversized nonce, causing a stack-based buffer overflow with potential remote code execution implications.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 1.25.2CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify PgBouncer installation and versionRun 'pgbouncer --version' or check the installed package (e.g., 'dpkg -l pgbouncer', 'rpm -q pgbouncer', or 'pip show pgbouncer')Affected if Installed version is lower than 1.25.2
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Verify SCRAM authentication is enabledInspect the pgbouncer.ini configuration file and look for 'auth_type' setting. Common locations: /etc/pgbouncer/pgbouncer.ini or /etc/pgbouncer.iniAffected if auth_type is set to 'scram' or 'scram-sha-256' (SCRAM-based authentication)
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Confirm PgBouncer connects to backend databasesCheck pgbouncer.ini for 'database' or 'pgbouncer' sections that define backend connections, or review the userlist file for SCRAM-authenticated usersAffected if PgBouncer is configured to connect to PostgreSQL backends using SCRAM authentication
You are affected if PgBouncer version is below 1.25.2 AND SCRAM authentication is enabled for backend connections, as the stack overflow occurs in the SCRAM authentication code path when processing server-final-message from backends.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped1.25.2
Upgrade PgBouncer to version 1.25.2 or later to obtain the patched SCRAM code. If immediate upgrade is not feasible, restrict database connections to trusted backends only to mitigate malicious server attacks.
PgBouncer 1.25.2
- 1. Back up your current PgBouncer configuration and data files
- 2. Download PgBouncer version 1.25.2 or later from the official source (www.pgbouncer.org)
- 3. Install the new version following standard PgBouncer installation procedures
- 4. Restore your configuration files
- 5. Start PgBouncer and verify it is running correctly
- 6. Test that client connections and SCRAM authentication work as expected
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-6665 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-6665 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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