Out-of-bounds write in Asterisk app_sms.c lets attackers crash Asterisk
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · Low
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA.
Summary
Asterisk, an open source private branch exchange and telephony toolkit, is affected in its asterisk and certified-asterisk packages. The app_sms.c module copies externally controlled SMS lengths into fixed in-struct buffers without sufficient bounds checks, which is an out-of-bounds write (CWE-787). A remote attacker with low privileges can corrupt memory or crash Asterisk, but only if the administrator explicitly uses the SMS dialplan application without ensuring that the data passed to it is valid.
Written with Claude Haiku 5.5 from the sources below · 2026-11-03
Description from the CNA
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, `app_sms.c` copies externally controlled `SMS` lengths into `fixed in-struct buffers` without sufficient bounds checks, allowing an attacker to corrupt memory or crash Asterisk. The administrator must explicitly use the `SMS` dialplan application, which is useful when routing calls to or from `analog devices`, and must not have ensured that data passed to the application is valid. 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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| asterisk | asterisk | before 20.20.1; 21.0.0-pre1 to before 21.12.3; 22.0.0-pre1 to before 22.10.1; 23.0.0-pre1 to before 23.4.1 | 20.20.1, 21.12.3, 22.10.1, 23.4.1 | Patch available | CNA |
| asterisk | certified-asterisk | before 20.7-cert11; 22.8-cert1-pre1 to before 22.8-cert3 | 20.7-cert11, 22.8-cert3 | Patch available | CNA |
- asterisk Vendorasterisk Affected before 20.20.1; 21.0.0-pre1 to before 21.12.3; 22.0.0-pre1 to before 22.10.1; 23.0.0-pre1 to before 23.4.1 Fixed in 20.20.1, 21.12.3, 22.10.1, 23.4.1 Patch available CNA
- certified-asterisk Vendorasterisk Affected before 20.7-cert11; 22.8-cert1-pre1 to before 22.8-cert3 Fixed in 20.7-cert11, 22.8-cert3 Patch available CNA
Remediation
Asterisk asterisk packages are fixed in 20.20.1, 21.12.3, 22.10.1 and 23.4.1. Certified Asterisk is fixed in 20.7-cert11 and 22.8-cert3. Upgrade to a fixed version.
Written with Claude Haiku 5.5 from the sources below · 2026-11-03
- Fix · CNA asterisk (asterisk) Fixed in 20.20.1, 21.12.3, 22.10.1, 23.4.1
- Fix · CNA certified-asterisk (asterisk) Fixed in 20.7-cert11, 22.8-cert3
Vendor assessments
Timeline
- 2026-10-27 Threatist record created from CVE-2026-57199
- 2026-11-02 Affected versions changed · Red Hat
- 2026-11-02 CVSS score added · Red Hat
- 2026-11-03 CISA SSVC decision points changed
References
Other 15
- https://github.com/asterisk/asterisk/security/advisories/GHSA-q9fr-m7g8-6ph5
- https://github.com/asterisk/asterisk/commit/15c66022dc441ec63d7bd5f53cf7f35db72964be
- https://github.com/asterisk/asterisk/commit/38a2059eb77a91a6b6e76eeba5875c2b96027368
- https://github.com/asterisk/asterisk/commit/59b74276f24ba104d859f3f05897c9b8d835a28a
- https://github.com/asterisk/asterisk/commit/60f4ef3deac6b9af30519b46c13f103264038b82
- https://github.com/asterisk/asterisk/commit/661d6a2fc5cc7744ab9d849ed3c73ae5066386df
- https://github.com/asterisk/asterisk/commit/7048a3841df99e090b9d87246600373581629c98
- https://github.com/asterisk/asterisk/commit/f46f63bd4d33665d336cf8b5998650b915222549
- https://github.com/asterisk/asterisk/releases/tag/20.20.1
- https://github.com/asterisk/asterisk/releases/tag/21.12.3
- https://github.com/asterisk/asterisk/releases/tag/22.10.1
- https://github.com/asterisk/asterisk/releases/tag/23.4.1
- https://github.com/asterisk/asterisk/releases/tag/certified-20.7-cert11
- https://github.com/asterisk/asterisk/releases/tag/certified-22.8-cert3
- https://github.com/asterisk/asterisk/tree/24.0.0-pre1
More asterisk vulnerabilities
- TI-2025-30244 Using malformed From header can forge identity with ";" or NULL in name portion CVSS 3.1HIGH 7.7
- TI-2023-27195 Asterisk susceptible to Denial of Service via DTLS Hello packets during call initiation CVSS 3.1HIGH 7.5
- TI-2024-28351 Asterisk allows `Write=originate` as sufficient permissions for code execution / `System()` dialplan CVSS 3.1HIGH 8.8
- TI-2025-00959 Asterisk Unsafe Shell Sourcing in safe_asterisk Leads to Local Privilege Escalation CVSS 4.0HIGH 7.0
- TI-2025-34699 Asterisk remotely exploitable leak of RTP UDP ports and internal resources CVSS 3.1MEDIUM 6.5
- TI-2025-31747 Asterisk is Vulnerable to Remote DoS and possible RCE Attacks During Memory Allocation CVSS 3.1MEDIUM 6.5
Sources
- CVE-2026-57199 · CVE Program
- CVE-2026-57199 · NVD
- FIRST EPSS
- CVE-2026-57199 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences