Description
Kamailio before 5.4.0, as used in Sip Express Router (SER) in Sippy Softswitch 4.5 through 5.2 and other products, allows a bypass of a header-removal protection mechanism via whitespace characters. This occurs in the remove_hf function in the Kamailio textops module. Particular use of remove_hf in Sippy Softswitch may allow skilled attacker having a valid credential in the system to disrupt internal call start/duration accounting mechanisms leading potentially to a loss of revenue.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | kamailio | 5.4.0-1 | — |
| Debian 13 | kamailio | 5.4.0-1 | — |
| Debian 12 | kamailio | 5.4.0-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | kamailio | 5.3.2-1ubuntu0.1~esm2 | USN-7416-1 |
| Ubuntu Pro 18.04 LTS | kamailio | 5.1.2-1ubuntu2+esm2 | USN-7416-1 |
| Ubuntu Pro 16.04 LTS | kamailio | 4.3.4-1.1ubuntu2.1+esm2 | USN-7416-1 |
Advisories 1
- USN-7416-1 kamailio vulnerabilities Ubuntu Security Notices (USN) · Jun 25, 2026