CVE-2021-31878 [Medium] | Security Vulnerability in Asterisk

CVE-2021-31878 is rated High Exploit Risk (72/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 2.43%). 1 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +2.24% over the last day, indicating growing attacker interest. Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

EDB-ID	Source	Kind	Published	Link
—	nvd_ref	exploit_tag		Exploit-DB ↗

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Link

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#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.19%	2.43%	+2.24%
2	2026-01-15	0.73%	0.19%	-0.54%
3	2025-12-18	—	0.73%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.19%

2.43%

+2.24%

2026-01-15

0.73%

0.19%

-0.54%

2025-12-18

—

0.73%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
6.5	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	2.8	3.6	[email protected]
4.0	2.0	MEDIUM	`AV:N/AC:L/Au:S/C:N/I:N/A:P` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:S) A single authentication is required. Confidentiality impact (C:N) No confidentiality impact. Integrity impact (I:N) No integrity impact. Availability impact (A:P) Partial availability impact.	8.0	2.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

6.5

3.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

2.8

3.6

[email protected]

4.0

2.0

MEDIUM

AV:N/AC:L/Au:S/C:N/I:N/A:P Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:L): Exploitation conditions are straightforward and predictable.
Authentication (AU:S): A single authentication is required.
Confidentiality impact (C:N): No confidentiality impact.
Integrity impact (I:N): No integrity impact.
Availability impact (A:P): Partial availability impact.

8.0

2.9

[email protected]

OS Trackers for CVE-2021-31878

vendor	priority	summary	link
`debian`	unimportant	CVE-2021-31878 unimportant priority: Debian including 1 source packages (asterisk), 2 status rows across 2 suites (bullseye, sid): resolved 2.	https://security-tracker.debian.org/tracker/CVE-2021-31878
`gentoo`	high	CVE-2021-31878: 1 GLSA(s) (202412-03), 1 atom(s) (net-misc/asterisk); latest impact high.	https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-31878
`ubuntu`	low	CVE-2021-31878 low priority: Ubuntu including 1 source packages (asterisk), 15 status rows across 15 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): ignored 7, needs-triage 6, DNE 1, not-affected 1.	https://ubuntu.com/security/CVE-2021-31878

Affected software / configurations for CVE-2021-31878

Vendor	Product	Version	Raw CPE
digium	asterisk	16.17.0	cpe:2.3:a:digium:asterisk:16.17.0:::::::*
digium	asterisk	16.18.0	cpe:2.3:a:digium:asterisk:16.18.0:::::::*
digium	asterisk	16.19.0	cpe:2.3:a:digium:asterisk:16.19.0:::::::*
digium	asterisk	18.3.0	cpe:2.3:a:digium:asterisk:18.3.0:::::::*
digium	asterisk	18.4.0	cpe:2.3:a:digium:asterisk:18.4.0:::::::*
digium	asterisk	18.5.0	cpe:2.3:a:digium:asterisk:18.5.0:::::::*

References for CVE-2021-31878

URL	Tags
http://downloads.asterisk.org/pub/security/AST-2021-007.html	Patch Vendor Advisory
http://packetstormsecurity.com/files/163638/Asterisk-Project-Security-Advisory-AST-2021-007.html	Patch Third Party Advisory VDB Entry
http://seclists.org/fulldisclosure/2021/Jul/48	Mailing List Patch Third Party Advisory
https://downloads.digium.com/pub/security/AST-2021-007.html	Patch Vendor Advisory
https://issues.asterisk.org/jira/browse/ASTERISK-29381	Exploit Issue Tracking Vendor Advisory

URL

CVE-2021-31878

Public exploit references (Exploit-DB) for CVE-2021-31878

Exploit prediction scoring system (EPSS) score for CVE-2021-31878

Common vulnerability scoring system (CVSS) metrics for CVE-2021-31878

Weakness enumeration for CVE-2021-31878

OS Trackers for CVE-2021-31878

Affected software / configurations for CVE-2021-31878

References for CVE-2021-31878