Asterisk: Server-Side Request Forgery
CVE-2022-26499 is a critical-severity server-side request forgery vulnerability in Asterisk from Digium, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 18.11.2 as the first without the flaw, so updating Asterisk to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 7.74% chance of exploitation within 30 days, which is in the top 5.28% of all scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Asterisk to 18.11.2 or a later version.
- Read the advisory on packetstormsecurity.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Digium | Asterisk | 16.15.0 through 16.25.1; 18.0 up to, but not including, 18.11.2; 19.0.0 through 19.3.1 | 18.11.2 |
| Debian | Debian Linux | 10.0; 11.0 | Not stated |
Version data comes from NVD's product matching. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 9.1 | Critical | NVD |
| CVSS 2.0 | 6.4 | Medium | NVD |
Official description
An SSRF issue was discovered in Asterisk through 19.x. When using STIR/SHAKEN, it's possible to send arbitrary requests (such as GET) to interfaces such as localhost by using the Identity header. This is fixed in 16.25.2, 18.11.2, and 19.3.2.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Server-Side Request Forgery
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
How developers prevent this class of flaw
- If there is a known list of applications, IP, hostname, and/or domains to which the product is allowed to communicate, then use allowlists to ensure that outgoing requests are restricted to these known entities. The allowlists could be in the application code or possibly enforced by firewalls or network segmentation.
- If the product is expected to be able to connect to arbitrary IP addresses or domains, consider using a denylist that includes private network addresses, internal domain names, etc. The denylist could be in the application code or possibly enforced by firewalls or network segmentation.
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Advisories
Third-party and government advisories
- lists.debian.org/debian-lts-announce/2022/11/msg00021.htmlIssue Tracking, Third Party Advisory
- debian.org/security/2022/dsa-5285Third Party Advisory
Other vulnerabilities in Asterisk
- 9.8 Critical severity
- 7.5 High severity
Recent Server-Side Request Forgery vulnerabilities
- 8.8 High severity
- 7.3 High severity
- 8.1 High severity
- 7.6 High severity
- 7.6 High severity
- 9.1 Critical severity
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