CVE-2026-11939: IBM Security Verify Access Log Forgery

CVE-2026-11939 Overview

IBM disclosed CVE-2026-11939, an audit log forgery vulnerability affecting IBM Security Verify Access and IBM Verify Identity Access. The flaw impacts Security Verify Access versions 10.0 through 10.0.9.2 and Verify Identity Access versions 11.0 through 11.0.3. The issue is categorized under [CWE-88] Improper Neutralization of Argument Delimiters in a Command.

An unauthenticated remote attacker can inject crafted content that corrupts audit log integrity. Forged audit records undermine incident response, compliance evidence, and forensic investigations tied to identity and access management activity.

Critical Impact
Attackers can tamper with audit log entries over the network without authentication, degrading the trustworthiness of security event records used for compliance and investigation.

Affected Products

IBM Security Verify Access 10.0 through 10.0.9.2
IBM Verify Identity Access 11.0 through 11.0.3
IBM Security Verify Access Container and Verify Identity Access Container editions

Discovery Timeline

2026-10-08 - CVE-2026-11939 published to NVD
2026-10-12 - Last updated in NVD database

Technical Details for CVE-2026-11939

Vulnerability Analysis

The vulnerability resides in the audit logging subsystem of IBM Security Verify Access and IBM Verify Identity Access. Both products handle authentication, authorization, and federation for enterprise identity workloads. Audit records produced by these components are relied upon as the authoritative trail for access decisions.

According to the IBM advisory, affected versions may be susceptible to audit log forgery. The attack vector is network-based, requires no privileges, and no user interaction. Confidentiality and availability are unaffected, but integrity is compromised because malicious input influences logged content.

Successful exploitation does not grant code execution or data theft. Instead, it allows an attacker to pollute the audit trail with falsified entries, hide legitimate activity behind spurious events, or impersonate the behavior of other principals in log output.

Root Cause

The underlying weakness is classified as [CWE-88], Improper Neutralization of Argument Delimiters in a Command. User-controllable data flows into audit log generation without adequate sanitization of delimiter characters. These characters can be interpreted as record or field separators by log parsers.

When attacker-supplied input includes line terminators or structured delimiters, downstream log consumers treat the injected fragment as a new, legitimate record. This produces log entries that appear authentic but originate from attacker payloads.

Attack Vector

An unauthenticated remote attacker submits requests containing crafted delimiter sequences to a network-exposed Verify Access or Verify Identity Access endpoint. The server processes the request and writes attacker-controlled strings into the audit log. See the IBM Support Advisory for product-specific exploitation context.

Detection Methods for CVE-2026-11939

Indicators of Compromise

Audit log records containing unexpected newline, carriage return, or field-separator characters inside user-supplied fields such as usernames, client identifiers, or request parameters.
Duplicate or out-of-sequence timestamps in Verify Access audit output that do not align with request volume.
Audit entries attributing actions to principals that did not authenticate during the referenced window.

Detection Strategies

Parse Verify Access and Verify Identity Access audit logs for control characters and delimiter tokens in fields that should contain only alphanumeric input.
Correlate audit records against authentication, reverse proxy, and web server access logs to identify entries that lack a corresponding request.
Baseline normal audit record structure and alert on records that deviate from the expected field count or encoding.

Monitoring Recommendations

Forward Verify Access and Verify Identity Access audit logs to a centralized analytics platform with integrity verification such as hashing or write-once storage.
Monitor the IBM management interfaces and reverse proxy endpoints for anomalous request bodies containing encoded CR, LF, or structured delimiter sequences.
Alert on sudden spikes in audit record volume or on records sourced from unauthenticated endpoints.

How to Mitigate CVE-2026-11939

Immediate Actions Required

Inventory all IBM Security Verify Access 10.0.x and IBM Verify Identity Access 11.0.x deployments, including containerized editions.
Apply the fixed releases referenced in the IBM Support Advisory as soon as change windows permit.
Preserve existing audit logs before upgrade so forensic analysis can distinguish legitimate records from potentially forged entries.

Patch Information

IBM has published remediation guidance in security bulletin node 7291628. Administrators should upgrade Security Verify Access beyond 10.0.9.2 and Verify Identity Access beyond 11.0.3 to the versions identified by IBM. Container images should be rebuilt from the patched base images rather than patched in place.

Workarounds

Restrict network reachability of Verify Access management and runtime endpoints to trusted administrative networks until patches are deployed.
Enable upstream input validation at reverse proxies or web application firewalls to strip CR, LF, and structured delimiter characters from request fields that reach audit logging code paths.
Increase retention and off-box replication of audit logs so forged entries can be cross-checked against independent telemetry sources.

bash

# Example WAF rule concept to strip CRLF from inbound parameters
# Replace with vendor-specific syntax for your reverse proxy or WAF
SecRule ARGS "@rx [\r\n]" \
  "id:1026119390,phase:2,deny,status:400,msg:'CRLF in parameter - potential audit log forgery (CVE-2026-11939)'"