Vulnerability · Published Oct 25, 2021 · Assigned by GitHub_M
CVE-2021-41105FreeSWITCH susceptible to Denial of Service via invalid SRTP packets
High 7.5
In plain English
A high-severity improper input validation in freeswitch from signalwire. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 2.5% (higher than 85% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to a software implementation that runs on any commodity hardware. When handling SRTP calls, FreeSWITCH prior to version 1.10.7 is susceptible to a DoS where calls can be terminated by remote attackers. This attack can be done continuously, thus denying encrypted calls during the attack. When a media port that is handling SRTP traffic is flooded with a specially crafted SRTP packet, the call is terminated leading to denial of service. This issue was reproduced when using the SDES key exchange mechanism in a SIP environment as well as when using the DTLS key exchange mechanism in a WebRTC environment. The call disconnection occurs due to line 6331 in the source file `switch_rtp.c`, which disconnects the call when the total number of SRTP errors reach a hard-coded threshold (100). By abusing this vulnerability, an attacker is able to disconnect any ongoing calls that are using SRTP. The attack does not require authentication or any special foothold in the caller's or the callee's network. This issue is patched in version 1.10.7.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | freeswitch | 1.10.7-r0 | ALPINE-CVE-2021-41105 |
| Alpine:v3.21 | freeswitch | 1.10.7-r0 | ALPINE-CVE-2021-41105 |
| Alpine:v3.22 | freeswitch | 1.10.7-r0 | ALPINE-CVE-2021-41105 |
| Alpine:v3.23 | freeswitch | 1.10.7-r0 | ALPINE-CVE-2021-41105 |
| Alpine:v3.24 | freeswitch | 1.10.7-r0 | ALPINE-CVE-2021-41105 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| signalwire | freeswitch | < 1.10.7 |
Weakness: CWE-20 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- https://github.com/signalwire/freeswitch/releases/tag/v1.10.7 x_refsource_MISC
- https://github.com/signalwire/freeswitch/security/advisories/GHSA-jh42-prph-gp36 x_refsource_CONFIRM
- 20211026 [ES2021-09] FreeSWITCH susceptible to Denial of Service via invalid SRTP packets mailing-list, x_refsource_FULLDISC