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Pgpool-II CVE-2026-92873

| EUVDEUVD-2026-89677 MEDIUM
Incorrect Implementation of Authentication Algorithm (CWE-303)
2026-09-30 jpcert GHSA-pxg9-2v62-434q
6.9
CVSS 4.0 · Vendor: jpcert
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Reach watchdog port on HA cluster
  2. Delivery
    Send crafted watchdog auth messages
  3. Exploit
    Bypass node authentication algorithm
  4. Execution
    Force arbitrary node to leader
  5. Impact
    Disrupt cluster failover/coordination

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A07:2025 - Authentication Failures
ASVS 5.0
V6 - Authentication Authentication algorithm review
Exploitation Conditions

Requires Pgpool-II deployed in watchdog-based high-availability clustering mode (use_watchdog enabled with multiple cooperating Pgpool-II nodes) and network reachability to the watchdog communication interface - the flaw lives in the watchdog node-authentication algorithm and has no meaning on a standalone single instance. Given that precondition, no authentication and no user interaction are needed (PR:N/UI:N) and complexity is low (AC:L). The principal limiting factor is the non-default HA/watchdog configuration; single-node or non-watchdog Pgpool-II deployments are not exposed, and exposure further assumes the watchdog port is reachable by the attacker rather than restricted to a trusted cluster network.

Impact

This is a genuine integrity/availability concern for Pgpool-II high-availability deployments, but its real-world scope is constrained by deployment prerequisites rather than exploit difficulty. The vendor CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N, VC:L/VI:L/VA:L) scores 6.9 and correctly reflects a network-reachable, low-complexity, unauthenticated flaw with low-magnitude impact across confidentiality, integrity, and availability. CWE-303 (incorrect implementation of an authentication algorithm) means the watchdog inter-node authentication can be defeated, letting an attacker force leader election. No EPSS score, no CISA KEV listing, and no public exploit code are provided, so this is no public exploit identified at time of analysis - real-world exploitation is speculative, not observed. The key limiting factor is that the vulnerable watchdog subsystem is only present when Pgpool-II is configured for clustered HA (use_watchdog enabled across multiple nodes), which is a common but non-default configuration. Net: a real priority for HA Pgpool-II operators (unauthenticated + network-reachable + cluster-control impact), but lower urgency for the many single-instance Pgpool-II deployments that never enable watchdog. No signals conflict; the main caveat is that impact magnitude (Low across the board) tempers the otherwise attractive unauthenticated-network exploit profile.

Exploit ScenarioDerived

An attacker with network reachability to the Pgpool-II watchdog port on an HA cluster sends crafted watchdog protocol messages that exploit the flawed authentication algorithm, bypassing node authentication. They coerce the cluster into promoting an attacker-influenced (or arbitrary) watchdog node to leader, disrupting failover coordination and the virtual-IP/quorum decisions the leader controls. No authentication is required (PR:N) and complexity is low, though no public proof-of-concept is available at time of analysis.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 30, 2026

Pgpool-II deployments that run in watchdog-based high-availability clustering mode can have an arbitrary watchdog node promoted to leader by an unauthenticated network attacker, because the node-authentication algorithm is implemented incorrectly (CWE-303). The flaw is only meaningful on multi-node clusters with use_watchdog enabled and where the watchdog communication interface is reachable by the attacker - standalone or non-watchdog instances are not exposed - so the practical risk is a genuine but deployment-constrained integrity and availability concern rather than a broadly exploitable one. No public exploit code was identified at time of analysis, and no CISA KEV entry or EPSS data was supplied; authentication is not required (CVSS PR:N) and no user interaction is needed (UI:N) once the watchdog precondition is met.

RemediationAI

No vendor-released patch version is confirmed in the supplied data, so the first action is to consult the vendor announcement at https://pgpool.net/news/2026-09-29/ and the JVN advisory at https://jvn.jp/en/jp/JVN22475874/ for the fixed release and upgrade Pgpool-II to that version across every node in the cluster, restarting and re-establishing the watchdog cluster so the corrected authentication logic is in effect everywhere. Where an immediate upgrade is not possible, compensating controls target the precondition rather than the bug: restrict the watchdog communication interface with host-based firewall rules or network ACLs so only the addresses of legitimate cluster peers can reach it, ideally on an isolated management VLAN - the trade-off is that misconfigured ACLs will break heartbeat and quorum, causing spurious failovers or a split cluster. If automatic failover and VIP management are not required, disabling the watchdog feature (use_watchdog off) removes the attack surface entirely, at the cost of losing automatic leader election, failover, and VIP ownership. Strengthen any available watchdog transport authentication/TLS settings and per-node authorization keys if supported by your release, noting that key rotation requires coordinated restarts. Finally, monitor Pgpool-II and system logs for unexpected watchdog node joins, unexplained leader promotions, or failover churn, and audit reachability of the watchdog interface from outside the trusted cluster network - detection is important because a successful leader promotion may otherwise present as ordinary HA behavior.

Affected VersionsENISA

Pgpool-II 3.5.x ≤4.2.x
Pgpool-II 4.7.0 ≤4.7.2
Pgpool-II 4.3.0 ≤4.3.20
Pgpool-II 4.6.0 ≤4.6.7
Pgpool-II 4.5.0 ≤4.5.12
Pgpool-II 4.4.0 ≤4.4.17

Affected Packages

euvd pgpool_ii no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Pgpool-II is a PostgreSQL middleware layer providing connection pooling, load balancing, replication management, and high availability. Its watchdog subsystem is a separate coordination component: multiple Pgpool-II nodes form a cluster, exchange heartbeat and status information over a dedicated watchdog communication interface, and run a leader-election/consensus process so that one node takes leadership to coordinate failover, quorum decisions, and virtual-IP ownership. Correct leader election depends on each node being able to cryptographically or algorithmically prove its identity to its peers. CWE-303 (Incorrect Implementation of an Authentication Algorithm) indicates that the peer-node authentication scheme does not implement the intended verification correctly - the identity/authenticity check for watchdog peers can be satisfied by a party that should not be able to pass it - and the resulting weakness lets an attacker influence the election outcome and have an arbitrary node promoted to leader. The CPE string cpe:2.3:a:pgpool_global_development_group:pgpool-ii:*:*:*:*:*:*:*:* carries a wildcard version, meaning the advisory scope covers Pgpool-II generally rather than a single pinned release line. Consistent with the independent assessment, exploitation requires the non-default HA configuration (use_watchdog enabled with multiple cooperating nodes) plus network reachability to the watchdog interface; the assessed vector is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L, i.e., unauthenticated remote reach with low complexity but only partial confidentiality, integrity, and availability impact and no scope change.

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Severity by source

Vendor (jpcert) PRIMARY 6.9 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N
vuln.today AI 7.3 HIGH

Unauthenticated network flaw in the watchdog auth algorithm (PR:N/AV:N/AC:L); promoting an arbitrary node to leader yields low-magnitude confidentiality, integrity, and availability impact on the cluster without scope change.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N

Primary rating from Vendor (jpcert).

CVSS VectorVendor: jpcert

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Vulnerable system: Confidentiality
Low
Vulnerable system: Integrity
Low
Vulnerable system: Availability
Low
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

Lifecycle Timeline

2
Severity Changed
Sep 30, 2026 - 08:22 NVD
HIGH MEDIUM
CVSS changed
Sep 30, 2026 - 08:22 NVD
7.3 (HIGH) 6.9 (MEDIUM)

DescriptionCVE.org

Pgpool-II contains an incorrect implementation of an authentication algorithm, which may allow an unauthenticated attacker to promote an arbitrary watchdog node to the leader node.

Threat Intelligence Overview

EPSS Score
0.3%
Top 78% exploitable
Prevalence
Medium
widely-used PostgreSQL pooling middleware, but watchdog HA is an opt-in subset
Social Media
1
Sightings
Data Quality
3 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.3%
Patch available No
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
Yes
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

34
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +34
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

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