CVE-2026-110952
Tenable Plugin
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AI Threat Summary
CVE-2026-110952 is a moderate vulnerability affecting the target software. Threat hunters should monitor for exploit attempts and apply vendor patches immediately.
Description
A Kafka broker that authenticates clients with SASL/OAUTHBEARER using the bundled JWKS-backed validator always verifies the JWT signature, but two further checks are only performed when explicitly configured: - The issuer (iss) claim is verified only when sasl.oauthbearer.expected.issuer is set. When it is unset, a validly-signed token carrying the expected audience is accepted regardless of which issuer minted it. - An audience (aud) claim is required only when sasl.oauthbearer.expected.audience is set. When it is unset, a validly-signed token that omits the aud claim is accepted. (A token that carries an aud claim is still rejected when no expected audience is configured.) Both options default to unset and have been documented as optional (Importance LOW) since KIP-768 (3.1.0). Impact: The exposure is realizable mainly in deployments whose JWKS endpoint serves signing keys for more than one issuer (a multi-tenant identity provider, an aggregated/shared JWKS, or shared signing keys): a token minted for a different issuer, or a token lacking an audience, may be accepted to authenticate — potentially as a higher-privileged principal. In a single-issuer deployment where the provider controls the iss claim and issues audience-scoped tokens, exposure is limited. The signature trust anchor remains enforced in all cases. This is distinct from CVE-2026-33557 (acceptance of unsigned/unvalidated tokens); here the signature is validated and only the issuer/audience checks are not enforced by default. Mitigation (all affected versions, no upgrade required): Set both sasl.oauthbearer.expected.issuer (to your provider's exact iss value) and sasl.oauthbearer.expected.audience (to the audience(s) your brokers expect), per listener. Brokers that set these perform exact-match issuer/audience checks and are not affected. Both have been available since 3.1.0. Resolution: - From Apache Kafka 4.4.0: a broker configured with a JWKS endpoint fails to start unless both sasl.oauthbearer.expected.issuer and sasl.oauthbearer.expected.audience are set (secure by default). Deployments that intentionally do not restrict the issuer and/or audience may opt out per axis with sasl.oauthbearer.allow.unverified.issuer=true and/or sasl.oauthbearer.allow.unverified.audience=true.
Attack Chain
Attacker identifies vulnerable service instances using Shodan, Censys, or active scanning
Attacker crafts malicious payload exploiting CVE-2026-110952 to achieve remote code execution
Attacker executes arbitrary OS commands or shellcode in the context of the vulnerable process
Attacker installs backdoor, cron job, or web shell for persistent access
Attacker uses compromised host as pivot point to access internal network resources
MITRE ATT&CK Techniques
Attacker exploits the vulnerability in an internet-facing service to gain initial access
Post-exploitation shell commands executed through the vulnerability
Attacker downloads malware or tools after gaining code execution
Indicators of Compromise
| Type | Value | Description | |
|---|---|---|---|
| user_agent | Mozilla/5.0 (compatible; exploit/1.0) |
Generic exploit scanner user agent pattern | |
| url | /api/vuln-endpoint?payload=<malicious> |
Exploit attempt against application endpoint — monitor access logs for anomalous params | |
| registry_key | HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\backdoor |
Persistence mechanism after successful RCE |
Remediation
Quick Facts
| CVE ID | CVE-2026-110952 |
| CVSS Score | N/A |
| Published | 2026-10-28 |
| Exploited | No |
| CISA KEV | No |
| PoC | Not public |