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Fencer Vulns
high 7.5

CVE-2021-41105 json

FreeSWITCH susceptible to Denial of Service via invalid SRTP packets

published 2021-10-25 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-28242

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.5%
EPSS 2.5% chance of exploitation in 30 days, percentile 84%
public exploits
0
none known

Summary

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.

Patch / fix

  • freeswitch freeswitch 1.10.7
  • freeswitch Alpine 3.24, Alpine 3.23, Alpine 3.22 +7 more 1.10.7-r0

alpine advisories ALPINE-CVE-2021-41105

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Exploit prediction

2.52% chance of exploitation in the next 30 days, higher than 84% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/signalwire/freeswitch/security/advisories/GHSA-jh42-prph-gp36 referenced PoC, tagged "exploit" by a source, unverified
  • seclists.org http://seclists.org/fulldisclosure/2021/Oct/43 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Affected products

  • signalwire freeswitch

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.