CVE-2021-33056
Description
Belledonne Belle-sip before 4.5.20, as used in Linphone and other products, can crash via an invalid From header in a SIP message.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
A crash vulnerability in Belledonne Belle-sip before 4.5.20 allows denial of service via a crafted SIP message with an invalid From header.
Vulnerability
Belle-sip before version 4.5.20 contains a crash vulnerability in its SIP message parser when processing a malformed From header. The parser fails to handle certain invalid header values, leading to a null pointer dereference or similar memory corruption. This affects all products using belle-sip, including Linphone.
Exploitation
An unauthenticated attacker can send a crafted SIP message containing an invalid From header to a vulnerable instance. No special network position or authentication is required; the attacker only needs to be able to deliver a SIP message to the target.
Impact
Successful exploitation causes the belle-sip process to crash, resulting in a denial of service (DoS). The crash may disrupt ongoing calls or prevent the service from handling further SIP messages until restarted.
Mitigation
The vulnerability is fixed in belle-sip version 4.5.20, released on June 10, 2021 [2]. Users should upgrade to this version or later. The fix is implemented in commit 116e3eb48fe43ea63eb9f3c4b4b30c48d58d6ff0 [1]. No workarounds are documented; upgrading is the recommended action.
AI Insight generated on May 27, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.
Affected products
2- Belledonne/Belle-sipdescription
- Range: <4.5.20
Patches
0No patches discovered yet.
Vulnerability mechanics
AI mechanics synthesis has not run for this CVE yet.
References
2- github.com/BelledonneCommunications/belle-sip/commit/116e3eb48fe43ea63eb9f3c4b4b30c48d58d6ff0mitrex_refsource_MISC
- github.com/BelledonneCommunications/belle-sip/compare/4.5.15...4.5.20mitrex_refsource_CONFIRM
News mentions
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