CVE-2021-21702 | Null Dereference in SoapClient

In PHP versions 7.3.x below 7.3.27, 7.4.x below 7.4.15 and 8.0.x below 8.0.2, when using SOAP extension to connect to a SOAP server, a malicious SOAP server could return malformed XML data as a response that would cause PHP to access a null pointer and thus cause a crash.

Published: 2021-02-15 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-21702 is rated Low Risk (38.1/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.25%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

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

Exploit prediction scoring system (EPSS) score for CVE-2021-21702

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 2025-12-28 0.21% 0.25% +0.04%
2 2025-12-27 0.25% 0.21% -0.04%
3 2025-11-21 — 0.25% —

Full EPSS history (27 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-21702

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:L/PR:N/UI:N/S:U/C:N/I:N/A:L 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:N)
No account or special rights needed—anonymous or random user is enough.
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:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 1.4 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/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:N)
No account or special rights needed—anonymous or random user is enough.
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.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/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:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-21702

OS Trackers for CVE-2021-21702

vendor priority summary link
alpine high CVE-2021-21702: 2 source package rows (php7, php8); 2 state rows across 1 repos (edge-community); fixed 2, open 0. https://security.alpinelinux.org/vuln/CVE-2021-21702
debian not yet assigned CVE-2021-21702 not yet assigned priority: Debian including 1 source packages (php7.4), 1 status rows across 1 suites (bullseye): resolved 1. https://security-tracker.debian.org/tracker/CVE-2021-21702
gentoo normal CVE-2021-21702: 1 GLSA(s) (202105-23), 1 atom(s) (dev-lang/php); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-21702
redhat low — https://access.redhat.com/security/cve/CVE-2021-21702
suse high CVE-2021-21702 severity important: SUSE including 807 source package names (apache2-mod_php5-5.2.14-111.77.1, apache2-mod_php53-5.3.17-112.99.2, …), 2085 product×package rows across 49 product lines (SUSE CaaS Platform 4.0, SUSE Enterprise Storage 6, … (49 product lines)): Fixed 1988, Known Not Affected 97. https://www.suse.com/security/cve/CVE-2021-21702/
ubuntu low CVE-2021-21702 low priority: Ubuntu including 6 source packages (php5, php7.0, php7.2, php7.4, php8.0, php8.1), 54 status rows across 9 suites (bionic, focal, groovy, hirsute, impish, jammy, trusty, upstream, xenial): DNE 40, released 7, needs-triage 4, not-affected 3. https://ubuntu.com/security/CVE-2021-21702

Affected software / configurations for CVE-2021-21702

Vendor Product Version Raw CPE
php php >= 7.3.0, < 7.3.27 cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
php php >= 7.4.0, < 7.4.15 cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
php php >= 8.0.0, < 8.0.2 cpe:2.3:a:php:php:*:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
netapp clustered_data_ontap — cpe:2.3:a:netapp:clustered_data_ontap:-:*:*:*:*:*:*:*
oracle communications_diameter_signaling_router >= 8.0.0, <= 8.5.0 cpe:2.3:a:oracle:communications_diameter_signaling_router:*:*:*:*:*:*:*:*

References for CVE-2021-21702

cvelogic Threat Intelligence