A use-after-free in res_pjsip_pubsub.c in Sangoma Asterisk 16.28, 18.14, 19.6, and certified/18.9-cert2 may allow a remote authenticated attacker to crash Asterisk (denial of service) by performing activity on a subscription via a reliable transport at the same time that Asterisk is also performing activity on that subscription.
https://www.debian.org/security/2023/dsa-5358
https://lists.debian.org/debian-lts-announce/2023/02/msg00029.html
https://downloads.asterisk.org/pub/security/AST-2022-008.html