Asterisk: Stack buffer overflow in MWI NOTIFY Message-Account parsing

Summary

Asterisk is an open source private branch exchange and telephony toolkit. Prior to Asterisk 20.20.1, 21.12.3, 22.10.1, 23.4.1 and Certified Asterisk 20.7-cert11, 22.8-cert3, an unbounded `sscanf` in `res_pjsip_pubsub` when parsing the `MWI NOTIFY` `Message-Account` field may allow an unauthenticated attacker to send a carefully crafted packet that causes a stack buffer overflow and corrupts the underlying transport, permanently disabling all SIP functionality. An Asterisk restart is required to restore full operation. This issue is fixed in Asterisk 20.20.1, 21.12.3, 22.10.1, 23.4.1 and Certified Asterisk 20.7-cert11, 22.8-cert3.

Remediation

1. Inventory every asterisk asterisk deployment, including staging.
2. No fixed version appears in the public sources yet. Check the references below and the vendor directly.

References

• Referencehttps://github.com/asterisk/asterisk/commit/0e89514084490070c5ecee419ec5ee37b7c49528
• Referencehttps://github.com/asterisk/asterisk/commit/647b35c3cfd4a2cc3b1fb7560b085feba5c24b4b
• Referencehttps://github.com/asterisk/asterisk/commit/7a1ffcdf38cc76d1c4eae51651667f3fd4548ab0
• Referencehttps://github.com/asterisk/asterisk/commit/b4be3bd67ce4ac35b94fbfa860cdd9e1c906610b
• Referencehttps://github.com/asterisk/asterisk/commit/b5281828dad7d44658439ba6393fe6be3328a4bd
• Referencehttps://github.com/asterisk/asterisk/commit/dca516f6d895e8867d48fa56b6ce7f05b6f7457a
• Referencehttps://github.com/asterisk/asterisk/commit/ee1b66a5e40733ba0b9fad7fc4d032cabbe1dd75
• Referencehttps://github.com/asterisk/asterisk/releases/tag/20.20.1
• Referencehttps://github.com/asterisk/asterisk/releases/tag/21.12.3
• Referencehttps://github.com/asterisk/asterisk/releases/tag/22.10.1
• Referencehttps://github.com/asterisk/asterisk/releases/tag/23.4.1
• Referencehttps://github.com/asterisk/asterisk/releases/tag/certified-20.7-cert11