Affects widely deployed Asterisk PBX; unauthenticated exploit can disable SIP telephony across organizations, causing significant business disruption.
CVE-2026-57191
Unauthenticated buffer overflow in Asterisk res_pjsip_pubsub via SIP MWI Message-Account
Is CVE-2026-57191 being exploited?
Not confirmed. CVE-2026-57191 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked.
How severe is CVE-2026-57191?
CVE-2026-57191 is rated High with a CVSS score of 8.2. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-57191?
Yes. A fix has been recorded for CVE-2026-57191. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-57191 affect?
CVE-2026-57191 affects Asterisk versions prior to 20.20.1, 21.12.3, 22.10.1, 23.4.1, Certified Asterisk prior to 20.7-cert11, 22.8-cert3. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-57191?
Upgrade to listed fixed Asterisk releases; block/inspect SIP NOTIFY from untrusted networks.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated remote stack buffer overflow via crafted SIP MWI NOTIFY Message-Account that corrupts transport and disables SIP functionality; requires restart.
Immediate action required
- affected< 20.20.1
- affected>= 21.0.0-pre1 and < 21.12.3
- affected>= 22.0.0-pre1 and < 22.10.1
- affected>= 23.0.0-pre1 and < 23.4.1
- affected< 20.7-cert11
- affected>= 22.8-cert1-pre1 and < 22.8-cert3
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.