Ubuntu USN-8786-1 Fixes rsyslog Vulnerability
Tech GuruQuick Answer
Ubuntu's USN-8786-1 fixes CVE-2026-78002 in rsyslog on the six releases listed below. Crafted network traffic can trigger a crash during string replacement. Install the package for the host's own Ubuntu release, then restart rsyslog as the advisory requires.
Confirm Scope And Apply The Supported Fix
What to do now: Identify rsyslog collectors and forwarding hosts, record their Ubuntu release and network inputs, apply the corresponding fixed package, coordinate the required restart, and confirm log delivery resumes.
Last verified: 2026-09-21 UTC. Recheck the authoritative advisory and supported distribution channel before changing production.
Scope And Authority
| Product scope | rsyslog vulnerability on Ubuntu 26.04 LTS (resolute), Ubuntu 24.04 LTS (noble), Ubuntu 22.04 LTS (jammy), Ubuntu 20.04 ESM (focal), Ubuntu 18.04 ESM (bionic), Ubuntu 16.04 ESM (xenial) |
|---|---|
| Advisory | USN-8786-1 |
| CVE | CVE-2026-78002 |
| Authoritative release date | 2026-09-21 12:22:06.547384 UTC |
| Authority revision date | 2026-09-21 12:22:06.547384 UTC |
| Affected versions | The Ubuntu releases and packages enumerated in USN-8786-1: Ubuntu 26.04 LTS (resolute), Ubuntu 24.04 LTS (noble), Ubuntu 22.04 LTS (jammy), Ubuntu 20.04 ESM (focal), Ubuntu 18.04 ESM (bionic), Ubuntu 16.04 ESM (xenial). |
| Fixed version | bionic: rsyslog 8.32.0-1ubuntu4.2+esm1 / focal: rsyslog 8.2001.0-1ubuntu1.3+esm1 / jammy: rsyslog 8.2112.0-2ubuntu2.5 / noble: rsyslog 8.2312.0-3ubuntu9.4 / resolute: rsyslog 8.2512.0-1ubuntu4.2 / xenial: rsyslog 8.16.0-1ubuntu3.1+esm3 |
| CVSS base score | Not provided by the authority |
| CVSS severity | Not provided by the authority |
| Exploitation status | Not stated by the authority; no exploitation claim is inferred. |
What Changed
Ubuntu identifies an incorrect buffer-size calculation when rsyslog replaces strings. A remote attacker may cause a crash and denial of service. The advisory explicitly requires an rsyslog restart after the system update; a completed package transaction is not the final validation step.
What To Validate Now
- Inventory. Record each rsyslog host's Ubuntu release, package version, enabled network inputs, forwarding destinations, and logging owner.
- Establish applicability. Compare each deployment with the authority's affected-version statement: The Ubuntu releases and packages enumerated in USN-8786-1: Ubuntu 26.04 LTS (resolute), Ubuntu 24.04 LTS (noble), Ubuntu 22.04 LTS (jammy), Ubuntu 20.04 ESM (focal), Ubuntu 18.04 ESM (bionic), Ubuntu 16.04 ESM (xenial). Do not infer applicability from product family or severity alone.
- Remediate. Apply bionic: rsyslog 8.32.0-1ubuntu4.2+esm1 / focal: rsyslog 8.2001.0-1ubuntu1.3+esm1 / jammy: rsyslog 8.2112.0-2ubuntu2.5 / noble: rsyslog 8.2312.0-3ubuntu9.4 / resolute: rsyslog 8.2512.0-1ubuntu4.2 / xenial: rsyslog 8.16.0-1ubuntu3.1+esm3 through the supported vendor or project channel, following the current advisory and change-control requirements.
- Validate. After the supported restart, confirm the package, daemon health, and receipt and forwarding of approved test messages. Check queue/destination health and preserve any logging-gap evidence.
- Retain evidence. Preserve asset and owner identifiers, the applicability decision, before-and-after versions, change approval, installation output, validation results, and any exception or rollback record.
Operational Cautions
Use the exact supported release stream and repository. Test dependencies, clusters, integrations, and rollback before broad deployment; a CVSS rating or reachable feature is not evidence of exploitation.
Evidence To Retain
- Exact product, release stream, package or application version, enabled feature, environment, and accountable owner.
- UTC timestamps, authority revision, approved change record, installer or package-manager output, and resulting version.
- Relevant logs and monitoring evidence, test results, exceptions, compensating controls, and rollback decisions.
Related TechGeeks Resources
Authoritative References
Correction policy: If the authority changes affected versions, fixed versions, severity, exploitation information, mitigations, or required action, TechGeeks will update this notice and its verification date.
