CVE-2021-41105 FreeSWITCH susceptible to Denial of Service via invalid SRTP packets
Remote attackers can terminate ongoing SRTP calls by flooding media ports with crafted packets, causing denial of service in FreeSWITCH.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-41105?
CVE-2021-41105 is a high-severity denial of service vulnerability in signalwire freeswitch, published on 25 Oct 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Weakness: CWE-20
Which versions are affected by CVE-2021-41105?
It affects 1 product.
Products include Freeswitch Freeswitch.
How do I fix CVE-2021-41105?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-41105 being exploited?
There is no known exploitation of CVE-2021-41105 in the wild and no public exploit code.
Other vulnerabilities in signalwire freeswitch
- CVE-2026-49841 FreeSWITCH: Pre-authentication heap buffer overflow in `mod_verto` HTTP POST body read
- CVE-2019-19492 Hardcoded credentials in n/a
- CVE-2026-49840 FreeSWITCH: Pre-authentication heap buffer overflow in libesl `Content-Length` parsing
- CVE-2021-41145 FreeSWITCH susceptible to Denial of Service via SIP flooding
- CVE-2026-45771 Freeswitch Denial-of-Service in SIP PUBLISH Requests via XML Entity Expansion
Sources
Also known as ALPINE-CVE-2021-41105, GHSA-jh42-prph-gp36.