FreeSWITCH: Stack buffer overflow parsing the SDP a=crypto key material on inbound calls
Affects FreeSWITCH versions before 1.11.2 on SIP profiles that accept inbound calls and parse SDES a=crypto offers. Fixed in 1.11.2.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 1.11.2
- Who is exposed
- Default setups
Do first: Check every install: default setups are affected.
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 30/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Default setups
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
FreeSWITCH, an open-source telecom switching platform, has a stack buffer overflow in how it parses SDP a=crypto key material on inbound calls. A remote, unauthenticated attacker can send a crafted call setup to crash the FreeSWITCH process, dropping all active calls, though remote code execution has not been demonstrated.
Read the original 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. Prior to 1.11.2, switch_core_media_add_crypto() passed the encoded key and salt length from an inbound SDP a=crypto attribute to switch_b64_decode() as the destination capacity. A zero-length key and salt made that capacity underflow, allowing the decoded attribute to overflow a fixed stack buffer with sender-chosen bytes before the call was answered. On the shipped external profile, an unauthenticated caller can reach the SDES-SRTP parser, while profiles that challenge inbound calls remain affected for senders who can authenticate; setting rtp_secure_media_inbound to false removes the path, and WebRTC DTLS-SRTP legs are unaffected. The overflow corrupts memory and can crash the FreeSWITCH process, dropping every active call, although remote code execution has not been demonstrated. This issue is fixed in version 1.11.2.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure22/25Default setups, reachable over the network without a login
- Reach?/20Unknown. No tracked technology or package matched
- Severity7.5/10CVSS 7.5
- No patch0/5No signal
What would change the score
- Would score about 70 if added to CISA KEV
- Would score about 65 if CISA's SSVC rates exploitation active
What to do
Check every install: default setups are affected.
Upgrade to a fixed version: 1.11.2.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- signalwire freeswitch
fixed in 1.11.2
Evidence 3
- Advisory
- Repository
- Repository
Corrections
None so far.
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Questions about CVE-2026-115928
Is CVE-2026-115928 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
A stack buffer overflow occurs when FreeSWITCH parses the a=crypto key material in an inbound SDP offer. The out-of-bounds write corrupts memory and crashes the FreeSWITCH process, dropping every call it is handling. Remote code execution has not been demonstrated.Source: github.com, github.com
Which versions are affected by CVE-2026-115928?
freeswitch: before 1.11.2.Source: cve.now feed data
Am I affected, and how do I check?
The flaw is in FreeSWITCH versions before 1.11.2, on any SIP profile that accepts inbound calls and processes INVITE offers that carry an SRTP media line with an SDES a=crypto attribute. WebRTC DTLS-SRTP legs are unaffected. Profiles that authenticate inbound calls challenge the sender before the offer is parsed, which limits the flaw to senders who can authenticate. Check the installed FreeSWITCH version and whether the relevant profiles accept inbound calls.Source: github.com, github.com
How do I fix CVE-2026-115928?
Upgrade FreeSWITCH to version 1.11.2 or later, which is the fixed release named in the FreeSWITCH v1.11.2 release notes.Source: github.com, github.com