CVE-2026-19086 Overview
CVE-2026-19086 is a buffer overflow vulnerability affecting IBM i versions 7.6, 7.5, 7.4, and 7.3. The flaw exists within a Portable Application Solutions Environment (PASE) process and enables an authenticated local attacker to trigger a denial of service (DoS). Exploitation is limited: the attacker can only terminate their own PASE process, not affect other users or system-wide services. The vulnerability is categorized under [CWE-125] Out-of-Bounds Read.
Critical Impact
An authenticated local attacker can crash their own PASE process through a buffer overflow, resulting in a limited denial of service condition.
Affected Products
- IBM i 7.6
- IBM i 7.5
- IBM i 7.4
- IBM i 7.3
Discovery Timeline
- 2026-09-14 - CVE-2026-19086 published to NVD
- 2026-09-16 - Last updated in NVD database
Technical Details for CVE-2026-19086
Vulnerability Analysis
The vulnerability resides in a Portable Application Solutions Environment (PASE) process on IBM i. PASE provides an AIX runtime environment within IBM i for executing AIX binaries. A buffer overflow condition, classified as an out-of-bounds read [CWE-125], can be triggered by an authenticated user interacting with the affected PASE process. The impact scope is confined to availability of the attacker's own process rather than the broader system. Confidentiality and integrity are not affected, and the attack requires local access with valid credentials.
Root Cause
The root cause is improper bounds checking within a PASE process routine, allowing memory access outside allocated buffer boundaries. When the out-of-bounds read occurs, the process encounters an invalid memory state and terminates. Because PASE processes run in the context of the invoking user, the impact remains scoped to that user's session.
Attack Vector
Exploitation requires local access to the IBM i system and authenticated user privileges. An attacker with a valid account submits crafted input to the vulnerable PASE process, triggering the buffer overflow. The resulting condition terminates the attacker's own process. No user interaction beyond the attacker is required. See the IBM Support Page for vendor-supplied technical details.
No public proof-of-concept exploit code is available for this vulnerability, and the vulnerability mechanism is described in prose only. Refer to IBM's advisory for further details on the affected PASE component.
Detection Methods for CVE-2026-19086
Indicators of Compromise
- Unexpected termination of PASE processes tied to a specific authenticated user
- Repeated abnormal process exits recorded in QSYSOPR message queue or QHST history log
- Job logs showing PASE runtime errors, signal terminations (SIGSEGV), or memory access exceptions
Detection Strategies
- Monitor IBM i audit journal (QAUDJRN) for repeated JB (job) and PW (invalid password/authority) entries associated with PASE process crashes
- Correlate PASE process termination events with the invoking user profile to detect anomalous patterns
- Establish a baseline of normal PASE runtime behavior and alert on deviations by a single user account
Monitoring Recommendations
- Ingest IBM i audit journal and system operator message queue events into a centralized SIEM for correlation
- Alert on repeated process termination events originating from the same authenticated user session within a short window
- Track privileged and service account activity accessing PASE binaries to identify unusual usage patterns
How to Mitigate CVE-2026-19086
Immediate Actions Required
- Apply the IBM-supplied Program Temporary Fix (PTF) referenced in the IBM Support Page for each affected release
- Inventory IBM i systems running versions 7.3, 7.4, 7.5, and 7.6 to determine patch scope
- Review authenticated user accounts with access to PASE and remove unnecessary local access privileges
Patch Information
IBM has released remediation guidance in the vendor advisory. Administrators should consult the IBM Support Page to identify the appropriate PTF for IBM i 7.3, 7.4, 7.5, and 7.6, then apply the fix through standard PTF installation procedures.
Workarounds
- Restrict access to PASE and the affected process to only trusted, required user profiles
- Apply the principle of least privilege to user profiles that can invoke PASE binaries
- Monitor and rate-limit repeated process crashes originating from the same user profile
# Example: review user profiles with access to PASE binaries on IBM i
# Run from a 5250 session or SSH into QSHELL/PASE
DSPUSRPRF USRPRF(*ALL) TYPE(*BASIC) OUTPUT(*OUTFILE) OUTFILE(QGPL/USRPRFS)
# Then review privileged classes (*SECOFR, *SECADM, *ALLOBJ) for excessive access
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
