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CVE-2021-37706

33
FAUCET Score

CVE-2021-37706 is a critical vulnerability in PJSIP, a multimedia communication library used by products like Asterisk and Debian. It involves an integer underflow when processing specially crafted STUN messages, allowing a malicious actor on the same network to remotely execute arbitrary code. With a CVSS score of 9.8, this vulnerability is highly severe, requiring no user interaction or complex attack conditions, and can lead to complete compromise of confidentiality, integrity, and availability. While no active exploitation or public exploit code is currently known, and community discussion is minimal, immediate upgrades are advised due to the high risk.

Impacted Technologies

VendorProductVersion(s)CPE
<= 2.11.1CPE matchmatch criteria
cpe:2.3:a:teluu:pjsip:*:*:*:*:*:*:*:*
< 16.8.0CPE matchmatch criteria
cpe:2.3:a:asterisk:certified_asterisk:*:*:*:*:*:*:*:*
16.8.0CPE matchmatch criteria
cpe:2.3:a:asterisk:certified_asterisk:16.8.0:*:*:*:*:*:*:*
16.8.0CPE matchmatch criteria
cpe:2.3:a:asterisk:certified_asterisk:16.8.0:cert1:*:*:*:*:*:*
16.8.0CPE matchmatch criteria
cpe:2.3:a:asterisk:certified_asterisk:16.8.0:cert10:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.3HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
LOW
Exploitability Score
3.9
Impact Score
3.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
4.62%
Probability of exploitation in next 30 days
EPSS Percentile
90.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0462 is in the 84th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (3)

github_advisorypatch availablevia nvd_reference
View patch
ubuntupatch availablevia ubuntu_usn
Product: pjproject (bionic)Fixed in: 2.7.2~dfsg-1ubuntu0.1~esm1
ubuntupatch availablevia ubuntu_usn
Product: pjproject (xenial)Fixed in: 2.1.0.0.ast20130823-1+deb8u1ubuntu0.1~esm1

Vendor Advisories (1)

ubuntuUSN-8122-1

PJSIP vulnerabilities

Mar 24, 2026

References

lists.debian.org / debian-lts-announce/2024/09/msg00030.html
packetstormsecurity.com / files/166225/Asterisk-Project-Security-Advisory-AST-2022-004.html
Third Party AdvisoryVDB Entry
seclists.org / fulldisclosure/2022/Mar/0
Mailing ListPatchThird Party Advisory
github.com / pjsip/pjproject/commit/15663e3f37091069b8c98a7fce680dc04bc8e865
PatchThird Party Advisory
github.com / pjsip/pjproject/security/advisories/GHSA-2qpg-f6wf-w984
PatchThird Party Advisory
lists.debian.org / debian-lts-announce/2022/03/msg00035.html
Mailing ListThird Party Advisory
lists.debian.org / debian-lts-announce/2022/11/msg00021.html
Mailing ListThird Party Advisory
lists.debian.org / debian-lts-announce/2023/08/msg00038.html
security.gentoo.org / glsa/202210-37
Third Party Advisory
debian.org / security/2022/dsa-5285
Third Party Advisory