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QSN-8840-1: libevent vulnerabilities
September 28, 2026
Summary
Several security issues were fixed in libevent.
Details
Michał Majchrowicz and Marcin Wyczechowski discovered that libevent incorrectly handled certain DNS responses. A remote attacker could possibly use this issue to cause a denial of service or execute arbitrary code. (CVE-2026-63387)
It was discovered that libevent incorrectly handled certain connections. A local attacker could possibly use this issue to cause a denial of service or execute arbitrary code. This issue only affected Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-63388)
Affected QuantaStor releases
| Release | Platform | Package | Exposure | Shipped version | Fixed version | Status |
|---|---|---|---|---|---|---|
| 6.9.1.001 | Ubuntu 22.04 LTS | libevent-core-2.1-7 | Internally-facing | 2.1.12-stable-1ubuntu0.2 | 2.1.12-stable-1ubuntu0.2 | Fixed in this release |
| 6.9.1.001 | Ubuntu 22.04 LTS | libevent-pthreads-2.1-7 | Internally-facing | 2.1.12-stable-1ubuntu0.2 | 2.1.12-stable-1ubuntu0.2 | Fixed in this release |
| 6.9.0.464 | Ubuntu 22.04 LTS | libevent-core-2.1-7 | Internally-facing | 2.1.12-stable-1ubuntu0.2 | 2.1.12-stable-1ubuntu0.2 | Fixed in this release |
| 6.9.0.464 | Ubuntu 22.04 LTS | libevent-pthreads-2.1-7 | Internally-facing | 2.1.12-stable-1ubuntu0.2 | 2.1.12-stable-1ubuntu0.2 | Fixed in this release |
| 6.8.6.015 | Ubuntu 22.04 LTS | libevent-core-2.1-7 | Internally-facing | 2.1.12-stable-1ubuntu0.1 | 2.1.12-stable-1ubuntu0.2 | Fixed by QuantaStor security update |
| 6.8.6.015 | Ubuntu 22.04 LTS | libevent-pthreads-2.1-7 | Internally-facing | 2.1.12-stable-1ubuntu0.1 | 2.1.12-stable-1ubuntu0.2 | Fixed by QuantaStor security update |
| 6.8.5.018 | Ubuntu 22.04 LTS | libevent-core-2.1-7 | Internally-facing | 2.1.12-stable-1build3 | 2.1.12-stable-1ubuntu0.2 | Fixed by QuantaStor security update |
| 6.8.5.018 | Ubuntu 22.04 LTS | libevent-pthreads-2.1-7 | Internally-facing | 2.1.12-stable-1build3 | 2.1.12-stable-1ubuntu0.2 | Fixed by QuantaStor security update |
| 6.8.4.038 | Ubuntu 22.04 LTS | libevent-core-2.1-7 | Internally-facing | 2.1.12-stable-1build3 | 2.1.12-stable-1ubuntu0.2 | Fixed by QuantaStor security update |
| 6.8.4.038 | Ubuntu 22.04 LTS | libevent-pthreads-2.1-7 | Internally-facing | 2.1.12-stable-1build3 | 2.1.12-stable-1ubuntu0.2 | Fixed by QuantaStor security update |
| 6.8.3.018 | Ubuntu 22.04 LTS | libevent-core-2.1-7 | Internally-facing | 2.1.12-stable-1build3 | 2.1.12-stable-1ubuntu0.2 | Fixed by QuantaStor security update |
| 6.8.3.018 | Ubuntu 22.04 LTS | libevent-pthreads-2.1-7 | Internally-facing | 2.1.12-stable-1build3 | 2.1.12-stable-1ubuntu0.2 | Fixed by QuantaStor security update |
| 6.8.2.002 | Ubuntu 22.04 LTS | libevent-core-2.1-7 | Internally-facing | 2.1.12-stable-1build3 | 2.1.12-stable-1ubuntu0.2 | Fixed by QuantaStor security update |
| 6.8.2.002 | Ubuntu 22.04 LTS | libevent-pthreads-2.1-7 | Internally-facing | 2.1.12-stable-1build3 | 2.1.12-stable-1ubuntu0.2 | Fixed by QuantaStor security update |
| 6.8.1.007 | Ubuntu 22.04 LTS | libevent-core-2.1-7 | Internally-facing | 2.1.12-stable-1build3 | 2.1.12-stable-1ubuntu0.2 | Fixed by QuantaStor security update |
| 6.8.1.007 | Ubuntu 22.04 LTS | libevent-pthreads-2.1-7 | Internally-facing | 2.1.12-stable-1build3 | 2.1.12-stable-1ubuntu0.2 | Fixed by QuantaStor security update |
| 6.8.0.205 | Ubuntu 22.04 LTS | libevent-core-2.1-7 | Internally-facing | 2.1.12-stable-1build3 | 2.1.12-stable-1ubuntu0.2 | Fixed by QuantaStor security update |
| 6.8.0.205 | Ubuntu 22.04 LTS | libevent-pthreads-2.1-7 | Internally-facing | 2.1.12-stable-1build3 | 2.1.12-stable-1ubuntu0.2 | Fixed by QuantaStor security update |
Internally-facing: only accessible when logged into the QuantaStor console/ssh as the qadmin administrative sudo user; generally lower priority. Externally-facing: part of a service the storage platform presents on the network (or the kernel), so potentially reachable over the network.
CVEs
CVE-2026-63387, CVE-2026-63388
References
https://ubuntu.com/security/notices/USN-8840-1
https://nvd.nist.gov/vuln/detail/CVE-2026-63387
https://nvd.nist.gov/vuln/detail/CVE-2026-63388
Update
Fixes marked Fixed by QuantaStor security update are applied by upgrading QuantaStor with security patches included (Upgrade Manager). Fixed package versions:
| Platform | Package | Version |
|---|---|---|
| bionic | libevent | 2.1.8-stable-4ubuntu0.1~esm2 |
| Ubuntu 20.04 LTS | libevent | 2.1.11-stable-1ubuntu0.1~esm2 |
| Ubuntu 22.04 LTS | libevent | 2.1.12-stable-1ubuntu0.2 |
| Ubuntu 24.04 LTS | libevent | 2.1.12-stable-9ubuntu2.2 |
| resolute | libevent | 2.1.12-stable-10ubuntu0.2 |
| trusty | libevent | 2.0.21-stable-1ubuntu1.14.04.2+esm2 |
| xenial | libevent | 2.0.21-stable-2ubuntu0.16.04.1+esm2 |