Evidence-led vulnerability intelligence · 2026-10-28 03:47 IST

CVE-2026-57191

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.

HIGH · 8.2

Executive briefing

The source record describes: 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. The practical risk depends on whether an affected product/version is present, reachable and configured in an exploitable way. Review the affected-product evidence and linked vendor advisories before assigning exposure status.

Assessment: Potential exposure only — validate the installed product, exact version, configuration and vendor applicability before treating an asset as confirmed vulnerable.

Evidence confidence: Limited Evidence-derived, not an exploitability verdict

Severity & attack characteristics

8.2 / 10 · 4.0

CVSS vector:
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack vectorN

Attack complexityH

Attack requirementsN

Privileges requiredN

User interactionN

ScopeX

Technical explanation & impact

The technical mechanism is not expanded beyond the source description unless a referenced advisory supplies additional evidence. Read the linked vendor/CERT advisories for root-cause detail.

Potential impact must be interpreted from the published CVSS impact metrics and the affected component. A CVSS impact score is not proof that a particular asset is exploitable.

Weakness classification

CWE-120CWE-787

Affected products and versions

NVD has not supplied machine-readable vulnerable CPE product/version entries for this CVE. This is an information gap, not proof that no products are affected. Check the vendor advisory references below.

Remediation & validation

Identify exposure by comparing the affected product and version ranges with your asset inventory, SBOM and externally exposed services.
Review the linked vendor security advisory or patch notes. Upgrade to a vendor-confirmed fixed release; do not infer a fixed version from the CVE description.
Until patched, consider restricting network access or disabling the affected feature where operationally safe. These are temporary controls, not a substitute for a vendor fix.
Validate the remediation with a version check and vulnerability rescan, then retain change evidence.

No fixed version is displayed unless it is explicitly established by a vendor advisory. Follow the vendor's release notes for exact product and branch applicability.

Vendor advisories, patches & exploit references

https://github.com/asterisk/asterisk/commit/0e89514084490070c5ecee419ec5ee37b7c49528 VENDOR security-advisories@github.com
https://github.com/asterisk/asterisk/commit/647b35c3cfd4a2cc3b1fb7560b085feba5c24b4b VENDOR security-advisories@github.com
https://github.com/asterisk/asterisk/commit/7a1ffcdf38cc76d1c4eae51651667f3fd4548ab0 VENDOR security-advisories@github.com
https://github.com/asterisk/asterisk/commit/b4be3bd67ce4ac35b94fbfa860cdd9e1c906610b VENDOR security-advisories@github.com
https://github.com/asterisk/asterisk/commit/b5281828dad7d44658439ba6393fe6be3328a4bd VENDOR security-advisories@github.com
https://github.com/asterisk/asterisk/commit/dca516f6d895e8867d48fa56b6ce7f05b6f7457a VENDOR security-advisories@github.com
https://github.com/asterisk/asterisk/commit/ee1b66a5e40733ba0b9fad7fc4d032cabbe1dd75 VENDOR security-advisories@github.com
https://github.com/asterisk/asterisk/releases/tag/20.20.1 VENDOR security-advisories@github.com
https://github.com/asterisk/asterisk/releases/tag/21.12.3 VENDOR security-advisories@github.com
https://github.com/asterisk/asterisk/releases/tag/22.10.1 VENDOR security-advisories@github.com
https://github.com/asterisk/asterisk/releases/tag/23.4.1 VENDOR security-advisories@github.com
https://github.com/asterisk/asterisk/releases/tag/certified-20.7-cert11 VENDOR security-advisories@github.com
https://github.com/asterisk/asterisk/releases/tag/certified-22.8-cert3 VENDOR security-advisories@github.com
https://github.com/asterisk/asterisk/security/advisories/GHSA-589g-qgf8-m6mx VENDOR security-advisories@github.com
https://github.com/asterisk/asterisk/tree/24.0.0-pre1 VENDOR security-advisories@github.com

Information gaps & confidence notes

These gaps indicate missing source data. CVE Watch does not fill them with guessed product, exploit or patch details.

NVD does not currently provide machine-readable vulnerable CPE product/version entries for this record.

Last enrichment: 2026-11-04T00:32:23+00:00 · Source last modified: 2026-11-02T20:17:45.527

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