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Fencer Vulns
high 7.3

CVE-2021-43804 json

Out-of-bounds read when parsing RTCP BYE message in PJSIP

published 2021-12-22 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-30695

cvss
7.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.3%
EPSS 2.3% chance of exploitation in 30 days, percentile 83%
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 affected versions if the incoming RTCP BYE message contains a reason's length, this declared length is not checked against the actual received packet size, potentially resulting in an out-of-bound read access. This issue affects all users that use PJMEDIA and RTCP. A malicious actor can send a RTCP BYE message with an invalid reason length. Users are advised to upgrade as soon as possible. There are no known workarounds.

Patch / fix

  • ring Debian 12 20230206.0~ds1-1
  • asterisk Debian 14 1:18.12.0~dfsg+~cs6.12.40431413-1

debian advisories DEBIAN-CVE-2021-43804

  • ring Ubuntu 20.04 LTS 20190215.1.f152c98~ds1-1+deb10u2build0.20.04.1
  • ring Ubuntu Pro 18.04 LTS 20180228.1.503da2b~ds1-1ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2021-43804

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 +6 more 2.12-r0

alpine advisories ALPINE-CVE-2021-43804

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-2021-43804 updated cvss 7.3

pjproject: Unchecked length in RTCP BYE message leads to out-of-bound read

  • 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

2.29% chance of exploitation in the next 30 days, higher than 83% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
NVD 3.1 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • pjsip pjproject

Classification

Weakness

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.