← Vulnerability feed

Vulnerability record · CVE-2018-17281 · published 24 September 2018

CVE-2018-17281: Asterisk res_http_websocket stack exhaustion via crafted HTTP upgrade request

Digium · Asterisk

Asterisk's res_http_websocket.so module has a stack consumption (uncontrolled resource consumption) flaw in versions through 13.23.0, 14.7.x through 14.7.7, 15.x through 15.6.0, and Certified Asterisk through 13.21-cert2. A specially crafted HTTP request that upgrades the connection to a websocket can exhaust the stack and crash the Asterisk process. Because Asterisk is a telephony platform, a crash takes down call handling and related services.

7.5 CVSS 3.0 High EPSS 53% · top 1.0% CWE-400 · Uncontrolled resource consumption
7.5CVSS 3.0 base score, v2 5.0
53%EPSS exploitation probability, 30 days
NoNot in CISA KEV
3Affected product versions listed by NVD
20References
17 Jun 2026Last modified by NVD

Description

There is a stack consumption vulnerability in the res_http_websocket.so module of Asterisk through 13.23.0, 14.7.x through 14.7.7, and 15.x through 15.6.0 and Certified Asterisk through 13.21-cert2. It allows an attacker to crash Asterisk via a specially crafted HTTP request to upgrade the connection to a websocket.

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 20 September 2026. Confidence: high.

high priorityUnauthenticated remote crash of a telephony service with a high EPSS score and available patches makes timely remediation important, though impact is limited to denial of service.

What it is

Asterisk's res_http_websocket.so module has a stack consumption (uncontrolled resource consumption) flaw in versions through 13.23.0, 14.7.x through 14.7.7, 15.x through 15.6.0, and Certified Asterisk through 13.21-cert2. A specially crafted HTTP request that upgrades the connection to a websocket can exhaust the stack and crash the Asterisk process. Because Asterisk is a telephony platform, a crash takes down call handling and related services.

Impact

An unauthenticated remote attacker can crash the Asterisk service, causing a denial of service that disrupts voice and telephony operations. No data confidentiality or integrity impact is described; the effect is availability loss.

Attack surface

Reachable over the network via the HTTP interface that handles websocket upgrade requests; the CVSS vector indicates no privileges and no user interaction are required. Any exposed Asterisk HTTP/websocket endpoint is a candidate path.

Exploitation

Not listed in CISA KEV and no ransomware association is documented, but EPSS is high (0.534, ~98.9th percentile), and multiple references carry Patch and Vendor Advisory tags, indicating a known, publicly documented flaw with fixes available.

What to do

  • Upgrade Asterisk to a fixed release per vendor advisory AST-2018-009 (and Debian DSA-4320 / Gentoo GLSA 201811-11 for packaged installs).
  • If immediate patching is not possible, restrict network access to the Asterisk HTTP/websocket interface to trusted sources only.
  • Disable or avoid exposing the HTTP websocket upgrade path where it is not operationally required.
  • Monitor and rate-limit HTTP requests to Asterisk to reduce the chance of stack-exhaustion crashes.
  • Track vendor advisories for the fixed versions covering your branch (13.x, 14.x, 15.x, Certified 13.x).

Detection

  • Alert on Asterisk process crashes or restarts correlated with inbound HTTP websocket upgrade requests.
  • Log and review HTTP requests to Asterisk containing websocket Upgrade headers, especially from unexpected sources.
  • Monitor for repeated or anomalous websocket upgrade attempts from single hosts as a possible DoS pattern.
  • Watch system logs for stack-related faults or core dumps in the Asterisk process.

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.

Affected products

3 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://downloads.asterisk.org/pub/security/AST-2018-009.html PatchVendor Advisory
http://packetstormsecurity.com/files/149453/Asterisk-Project-Security-Advisory-AST-2018-009.html Third Party AdvisoryVDB Entry
http://seclists.org/fulldisclosure/2018/Sep/31 Mailing ListPatchThird Party Advisory
http://www.securityfocus.com/bid/105389 Third Party AdvisoryVDB Entry
http://www.securitytracker.com/id/1041694 Third Party AdvisoryVDB Entry
https://issues.asterisk.org/jira/browse/ASTERISK-28013 Issue TrackingThird Party Advisory
https://lists.debian.org/debian-lts-announce/2018/09/msg00034.html Mailing ListThird Party Advisory
https://seclists.org/bugtraq/2018/Sep/53 Mailing ListPatchThird Party Advisory
https://security.gentoo.org/glsa/201811-11 Third Party Advisory
https://www.debian.org/security/2018/dsa-4320 Third Party Advisory
http://downloads.asterisk.org/pub/security/AST-2018-009.html PatchVendor Advisory
http://packetstormsecurity.com/files/149453/Asterisk-Project-Security-Advisory-AST-2018-009.html Third Party AdvisoryVDB Entry
http://seclists.org/fulldisclosure/2018/Sep/31 Mailing ListPatchThird Party Advisory
http://www.securityfocus.com/bid/105389 Third Party AdvisoryVDB Entry
http://www.securitytracker.com/id/1041694 Third Party AdvisoryVDB Entry
https://issues.asterisk.org/jira/browse/ASTERISK-28013 Issue TrackingThird Party Advisory
https://lists.debian.org/debian-lts-announce/2018/09/msg00034.html Mailing ListThird Party Advisory
https://seclists.org/bugtraq/2018/Sep/53 Mailing ListPatchThird Party Advisory
https://security.gentoo.org/glsa/201811-11 Third Party Advisory
https://www.debian.org/security/2018/dsa-4320 Third Party Advisory

Track CVE-2018-17281 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

10.0CVE-2025-32433Erlang/OTP SSH server missing authentication allows remote code executionErlang/OTP SSH servers before OTP-27.3.3, OTP-26.2.5.11 and OTP-25.3.2.20 mishandle SSH protocol messages, letting an unauthenticated attacker execut…KEVEPSS 99%analysed10.0CVE-2025-24201Apple WebKit out-of-bounds write allows sandbox escapeCVE-2025-24201 is an out-of-bounds write in Apple's WebKit that was addressed with improved checks. Maliciously crafted web content may break out of …KEVEPSS 3.8%analysed10.0CVE-2021-44228Apache Log4j2 JNDI lookup remote code executionApache Log4j2 versions 2.0-beta9 through 2.15.0 (excluding 2.12.2, 2.12.3, and 2.3.1) do not protect against attacker-controlled LDAP and other JNDI …KEVEPSS 100%analysed9.8CVE-2026-24061GNU Inetutils telnetd argument injection allows remote auth bypasstelnetd in GNU Inetutils through 2.7 fails to sanitize the USER environment variable, so a value such as "-f root" is passed as an argument to login …KEVEPSS 99%analysed9.8CVE-2025-39682Linux kernel TLS zero-length record handling flaw on rx_listThe Linux kernel TLS receive path mishandles zero-length records that arrive from the rx_list, breaking the assumption that a record type change cann…KEVEPSS 2.9%analysed9.8CVE-2025-24813Apache Tomcat Default Servlet path equivalence enables RCE and file disclosureApache Tomcat mishandles path equivalence for names containing an internal dot, letting a remote unauthenticated attacker write files through the Def…KEVEPSS 100%analysed9.8CVE-2024-9680Mozilla Firefox and Thunderbird use-after-free in Animation timelinesA use-after-free flaw in Animation timelines allows an attacker to execute code in the content process of Firefox and Thunderbird. Mozilla reports ex…KEVEPSS 23%analysed9.8CVE-2023-46604Apache ActiveMQ OpenWire deserialization remote code executionThe Java OpenWire protocol marshaller in Apache ActiveMQ deserializes untrusted data, letting an attacker manipulate serialized class types so the br…KEVEPSS 100%analysed

Source: NIST National Vulnerability Database (record CVE-2018-17281), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.