CVE-2026-16529
Description
A signed integer overflow in the PCP __pmGetPDU() function can be exploited via crafted network packets during PDU processing or SASL negotiation. This permanently blinds the affected daemon, resulting in a total denial of service (DoS) for subsequent packet reads.
Statement
This is an Important denial of service vulnerability in PCP due to a signed integer overflow. An unauthenticated remote attacker could exhaust resources by sending a specially crafted request to the pmlogger or pmcd services, leading to a permanent denial of service for the affected daemon. While both services are typically bound to the loopback interface by default, remote exploitation is possible if the default binding configuration is altered or if PMLOGGER_LOCAL is unset for pmlogger.
Mitigation
To mitigate this issue, ensure that Performance Co-Pilot (PCP) services, specifically `pmlogger` and `pmcd`, are not exposed to untrusted networks. By default, these services are configured to listen only on the loopback interface, which prevents remote exploitation. If these default network bindings have been altered, revert them to restrict access to localhost. For `pmlogger`, ensure the `PMLOGGER_LOCAL` environment variable is set. If remote access to PCP services is not required, consider implementing firewall rules to block external connections to TCP ports 4330 (pmlogger) and 44321 (pmcd). Changes to network configurations or environment variables may require restarting the affected PCP services for the mitigation to take effect.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (Memory); DoS: Instability
This weakness can generally lead to undefined behavior and therefore crashes. When the calculated result is used for resource allocation, this weakness can cause too many (or too few) resources to be allocated, possibly enabling crashes if the product requests more resources than can be provided.
Integrity
Technical Impact: Modify Memory
If the value in question is important to data (as opposed to flow), simple data corruption has occurred. Also, if the overflow/wraparound results in other conditions such as buffer overflows, further memory corruption may occur.
Confidentiality,Availability,Access Control
Technical Impact: Execute Unauthorized Code or Commands; Bypass Protection Mechanism
This weakness can sometimes trigger buffer overflows, which can be used to execute arbitrary code. This is usually outside the scope of the product's implicit security policy.
Availability,Other
Technical Impact: Alter Execution Logic; DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU)
If the overflow/wraparound occurs in a loop index variable, this could cause the loop to terminate at the wrong time - too early, too late, or not at all (i.e., infinite loops). With too many iterations, some loops could consume too many resources such as memory, file handles, etc., possibly leading to a crash or other DoS.
Access Control
Technical Impact: Bypass Protection Mechanism
If integer values are used in security-critical decisions, such as calculating quotas or allocation limits, integer overflows can be used to cause an incorrect security decision.
Acknowledgements
Red Hat would like to thank Francisco Alisson Bezerra (TIM Security Red Team Research, TIM S.p.A), Lucas Gabriel Alves (TIM Security Red Team Research, TIM S.p.A), and Massimiliano Brolli (TIM Security Red Team Research, TIM S.p.A) for reporting this issue.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
