CVE-2020-28327

Exp

A res_pjsip_session crash was discovered in Asterisk Open Source 13.x before 13.37.1, 16.x before 16.14.1, 17.x before 17.8.1, and 18.x before 18.0.1. and Certified Asterisk before 16.8-cert5. Upon receiving a new SIP Invite, Asterisk did not return the created dialog locked or referenced. This caused a gap between the creation of the dialog object, and its next use by the thread that created it. Depending on some off-nominal circumstances and timing, it was possible for another thread to free said dialog in this gap. Asterisk could then crash when the dialog object, or any of its dependent objects, were dereferenced or accessed next by the initial-creation thread. Note, however, that this crash can only occur when using a connection-oriented protocol (e.g., TCP or TLS, but not UDP) for SIP transport. Also, the remote client must be authenticated, or Asterisk must be configured for anonymous calling.

Published: 2020-11-06 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-28327 is rated High Exploit Risk (65.3/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 2.19%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2020-28327

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

Exploit prediction scoring system (EPSS) score for CVE-2020-28327

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-30 2.76% 2.19% -0.58%
2 2025-11-21 1.59% 2.76% +1.17%
3 2025-11-18 — 1.59% —

Full EPSS history (13 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-28327

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/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:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
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.
 1.6 3.6 [email protected]
2.1 2.0 LOW
AV:N/AC:H/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:H)
Exploitation requires uncommon or highly specific conditions.
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.
 3.9 2.9 [email protected]

Weakness enumeration for CVE-2020-28327

OS Trackers for CVE-2020-28327

vendor priority summary link
alpine medium CVE-2020-28327: 1 source package rows (asterisk); 8 state rows across 8 repos (3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 8, open 0. https://security.alpinelinux.org/vuln/CVE-2020-28327
debian not yet assigned CVE-2020-28327 not yet assigned priority: Debian including 1 source packages (asterisk), 2 status rows across 2 suites (bullseye, sid): resolved 2. https://security-tracker.debian.org/tracker/CVE-2020-28327
ubuntu low CVE-2020-28327 low priority: Ubuntu including 1 source packages (asterisk), 16 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 10, needed 3, DNE 1, ignored 1, released 1. https://ubuntu.com/security/CVE-2020-28327

Affected software / configurations for CVE-2020-28327

Vendor Product Version Raw CPE
digium certified_asterisk 16.8 cpe:2.3:a:digium:certified_asterisk:16.8:-:*:*:*:*:*:*
digium certified_asterisk 16.8 cpe:2.3:a:digium:certified_asterisk:16.8:cert1-rc1:*:*:*:*:*:*
digium certified_asterisk 16.8 cpe:2.3:a:digium:certified_asterisk:16.8:cert1-rc2:*:*:*:*:*:*
digium certified_asterisk 16.8 cpe:2.3:a:digium:certified_asterisk:16.8:cert1-rc3:*:*:*:*:*:*
digium certified_asterisk 16.8 cpe:2.3:a:digium:certified_asterisk:16.8:cert1-rc4:*:*:*:*:*:*
digium certified_asterisk 16.8 cpe:2.3:a:digium:certified_asterisk:16.8:cert2:*:*:*:*:*:*
digium certified_asterisk 16.8 cpe:2.3:a:digium:certified_asterisk:16.8:cert3:*:*:*:*:*:*
digium certified_asterisk 16.8 cpe:2.3:a:digium:certified_asterisk:16.8:cert4:*:*:*:*:*:*
digium certified_asterisk 16.8 cpe:2.3:a:digium:certified_asterisk:16.8:cert4-rc1:*:*:*:*:*:*
digium certified_asterisk 16.8 cpe:2.3:a:digium:certified_asterisk:16.8:cert4-rc2:*:*:*:*:*:*
digium certified_asterisk 16.8 cpe:2.3:a:digium:certified_asterisk:16.8:cert4-rc3:*:*:*:*:*:*
digium certified_asterisk 16.8 cpe:2.3:a:digium:certified_asterisk:16.8:cert4-rc4:*:*:*:*:*:*
sangoma asterisk >= 13.0.0, < 13.37.1 cpe:2.3:a:sangoma:asterisk:*:*:*:*:*:*:*:*
sangoma asterisk >= 16.0.0, < 16.14.1 cpe:2.3:a:sangoma:asterisk:*:*:*:*:*:*:*:*
sangoma asterisk >= 17.0.0, < 17.8.1 cpe:2.3:a:sangoma:asterisk:*:*:*:*:*:*:*:*
sangoma asterisk >= 18.0.0, < 18.0.1 cpe:2.3:a:sangoma:asterisk:*:*:*:*:*:*:*:*

References for CVE-2020-28327

cvelogic Threat Intelligence