How severe is CVE-2021-43678?

CVE-2021-43678 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2021-43678?

CVE-2021-43678 affects the following packages: gaoming13/wechat-php-sdk (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2021-43678?

No patched version of gaoming13/wechat-php-sdk has shipped for CVE-2021-43678 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

How do I detect CVE-2021-43678 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for gaoming13/wechat-php-sdk, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-43678 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2021-43678 actively exploited in the wild?

Yes. There are 2 known exploit references for CVE-2021-43678, including 2 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-43678?

CVE-2021-43678 has an EPSS (Exploit Prediction Scoring System) score of 0.8%, placing it in the 54th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-43678?

CVE-2021-43678 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2021-43678 published, and has it been updated?

CVE-2021-43678 was published on December 17, 2021 and was last updated on July 8, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘

🐘 Packagist

Not in CISA KEV

MEDIUM severity

CVE-2021-43678 — wechat-php-sdk

MEDIUM

CVE-2021-43678 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in gaoming13/wechat-php-sdk. 2 public exploit references exist, so weaponization risk is real. No vendor fix is recorded yet; mitigation options are listed below.

Wechat-php-sdk is affected by a Cross Site Scripting vulnerability.

Also known asGHSA-rwqq-p4p9-5wpq

Published

Dec 17, 2021

Updated

Jul 8, 2026

Affected

1 pkg

Patched

See advisory

Exploits

2 known

Exploitation data as of Oct 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.8%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs54th percentile — riskier than 54% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-43678 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,386 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

🐘gaoming13/wechat-php-sdk

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

Wechat-php-sdk v1.10.2 is affected by a Cross Site Scripting (XSS) vulnerability in Wechat.php.

Affected Packages

1 total

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`gaoming13/wechat-php-sdk`	all versions	No fix

Affected Products

1 product · 1 configurations

Application

wechat-php-sdkwechat-php-sdk_project

1 version

1.10.2

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Wechat-php-sdk v1.10.2 is affected by a Cross Site Scripting (XSS) vulne…

github.comNVDDec 2021

Wechat-php-sdk v1.10.2 is affected by a Cross Site Scripting (XSS) vulne…

github.comNVDDec 2021

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for gaoming13/wechat-php-sdk, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of gaoming13/wechat-php-sdk has shipped for CVE-2021-43678 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

Wechat-php-sdk v1.10.2 is affected by a Cross Site Scripting (XSS) vulnerability in Wechat.php.

O3 Security · Impact-Aware SCA

Is CVE-2021-43678 in your dependencies?

Find it across Packagist, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

6.1/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Raw vector

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

CWE Classification

CWE-79Cross-site Scripting (XSS)

Weaponization

No known public exploit tooling found.

Timeline

Disclosed

Dec 17, 2021

First exploit

Dec 21, 2021

4 days after disclosure — rapid exploitation

Last updated

Jul 8, 2026

Identifiers

CVE-2021-43678

GHSA-rwqq-p4p9-5wpq

References

Advisorynvd.nist.gov Evidencegithub.com Evidencegithub.com

Related vulnerabilities

This CVE is medium severity; 8 of 8 other CVEs with CWE-79 are rated as high or higher (top: high).

CVE-2026-91127CVE-2026-77606CVE-2026-84992CVE-2026-77608CVE-2026-77607GHSA-9rcc-pmj8-ffhrCVE-2026-77616CVE-2025-61682Browse all CWE-79

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedJul 8, 2026