Security readout for executives and security teams
Plain-English summary
A PHP application that uses SoapClient could be crashed by a malicious SOAP server returning malformed XML. The cited impact is availability loss only: no confidentiality or integrity impact is described. Business urgency depends on whether production PHP services call SOAP endpoints, especially external or less trusted ones.
Executive priority
Treat as a targeted availability risk, not a broad data breach issue. Prioritize patching where PHP services depend on SOAP integrations for customer-facing or operational workflows, especially if external SOAP providers are involved.
Technical view
CVE-2021-21702 is a CWE-476 null pointer dereference in PHP's SOAP extension. PHP 7.3.x before 7.3.27, 7.4.x before 7.4.15, and 8.0.x before 8.0.2 can crash when SoapClient processes malformed XML returned by a malicious SOAP server.
Likely exposure
Exposure is most likely in PHP applications with the SOAP extension enabled and code using SoapClient to connect to SOAP servers. Risk is higher when those servers are third-party, internet-facing, compromised, or otherwise not fully trusted.
Exploitation context
The source describes a malicious SOAP server causing a PHP crash through malformed XML. KEV status is false, and the provided sources do not support active exploitation claims. Exploitation appears limited to availability impact and requires the target application to consume the malicious SOAP response.
Researcher notes
The provided evidence is specific to PHP SoapClient behavior with malformed XML returned by a SOAP server. No exploit code, active exploitation, or broader impact is cited. Validate exposure by combining runtime version checks with application-level SOAP client usage review.
Mitigation direction
- Upgrade PHP to 7.3.27, 7.4.15, 8.0.2, or a supported later release.
- Apply applicable Debian, Gentoo, Oracle, NetApp, or other vendor package updates.
- Identify applications using PHP SoapClient and prioritize externally dependent SOAP integrations.
- Review vendor guidance for packaged products that embed or depend on affected PHP versions.
Validation and detection
- Inventory production PHP versions and confirm none are below the fixed version thresholds.
- Verify whether the SOAP extension is enabled on PHP runtimes.
- Search application dependencies and code ownership records for SoapClient usage.
- Map SOAP endpoints consumed by affected applications and identify third-party or untrusted services.
- Confirm operating-system or appliance vendor advisories have been applied where relevant.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-476: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-21702 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L3.91.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.3MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Source materials
- CVE List V5 sourceCVE List V5
- https://bugs.php.net/bug.php?id=80672CVE reference · x_refsource_MISC
- DSA-4856CVE reference · vendor-advisory, x_refsource_DEBIAN
- GLSA-202105-23CVE reference · vendor-advisory, x_refsource_GENTOO
- [debian-lts-announce] 20210715 [SECURITY] [DLA 2708-1] php7.0 security updateCVE reference · mailing-list, x_refsource_MLIST
- https://www.oracle.com/security-alerts/cpuoct2021.htmlCVE reference · x_refsource_MISC
- https://www.tenable.com/security/tns-2021-14CVE reference · x_refsource_CONFIRM
- https://security.netapp.com/advisory/ntap-20210312-0005/CVE reference · x_refsource_CONFIRM
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
NULL Pointer Dereference
NULL Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.