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Fencer Intel
medium 5.4

CVE-2020-28361 json

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 hea…

published 5y ago modified 4mo ago also EUVD-2020-20821

cvss
5.4
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.1%
EPSS 1.1% chance of exploitation in 30 days, percentile 66%
public exploits
0
none known

Summary

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.

Patch / fix

  • kamailio kamailio 5.4.0
  • kamailio Debian 14, Debian 13, Debian 12 5.4.0-1

debian advisories DEBIAN-CVE-2020-28361

  • kamailio Ubuntu Pro 18.04 LTS 5.1.2-1ubuntu2+esm2
  • kamailio Ubuntu Pro 20.04 LTS 5.3.2-1ubuntu0.1~esm2

ubuntu advisories UBUNTU-CVE-2020-28361

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

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Exploit prediction

1.11% chance of exploitation in the next 30 days, higher than 66% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • packetstormsecurity.com https://packetstormsecurity.com/files/159030/Kamailio-5.4.0-Header-Smuggling.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
NVD 2.0 5.5 AV:N/AC:L/Au:S/C:P/I:P/A:N

Classification

Weakness
  • CWE-444 Inconsistent Interpretation of HTTP Requests

References

Sources

Fencer Intel 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.