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Fencer Vulns
medium 6.5

CVE-2021-21375 json

Crash in receiving updated SDP answer after initial SDP negotiation failed

published 2021-03-10 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-8685

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.1%
EPSS 2.1% chance of exploitation in 30 days, percentile 81%
public exploits
0
none known

Summary

PJSIP is a free and open source multimedia communication library written in C language implementing standard based protocols such as SIP, SDP, RTP, STUN, TURN, and ICE. In PJSIP version 2.10 and earlier, after an initial INVITE has been sent, when two 183 responses are received, with the first one causing negotiation failure, a crash will occur. This results in a denial of service.

Patch / fix

  • ring Debian 12 20210112.2.b757bac~ds1-1

debian advisories DEBIAN-CVE-2021-21375

  • pjproject Ubuntu Pro 16.04 LTS 2.1.0.0.ast20130823-1+deb8u1ubuntu0.1~esm1
  • pjproject Ubuntu Pro 18.04 LTS 2.7.2~dfsg-1ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2021-21375

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

  • pjproject Alpine 3.24, Alpine 3.23, Alpine 3.22 +8 more 2.11-r0

alpine advisories ALPINE-CVE-2021-21375

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

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-21375 updated cvss 6.5

pjproject: crash in receiving updated SDP answer after initial SDP negotiation failed

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.08% chance of exploitation in the next 30 days, higher than 81% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/pjsip/pjproject/security/advisories/GHSA-hvq6-f89p-frvp referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:N/A:P

Affected products

  • pjsip pjproject

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-754 Improper Check for Unusual or Exceptional Conditions

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.