Description
posix/JackSocket.cpp in libjack in JACK2 1.9.1 through 1.9.12 (as distributed with alsa-plugins 1.1.7 and later) has a "double file descriptor close" issue during a failed connection attempt when jackd2 is not running. Exploitation success depends on multithreaded timing of that double close, which can result in unintended information disclosure, crashes, or file corruption due to having the wrong file associated with the file descriptor.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | jackd2 | 1.9.14~dfsg-0.1 | — |
| Debian 13 | jackd2 | 1.9.14~dfsg-0.1 | — |
| Debian 12 | jackd2 | 1.9.14~dfsg-0.1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | jackd2 | 1.9.12~dfsg-2ubuntu2 | — |
| Ubuntu 18.04 LTS | jackd2 | No fix yet | — |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 16.04 LTS | jackd2 | 1.9.10+20150825git1ed50c92~dfsg-1ubuntu1+esm1 | USN-5656-1 |
Advisories 1
- USN-5656-1 jackd2 vulnerability Ubuntu Security Notices (USN) · Jun 25, 2026