CVE-2021-29476 is a critical-severity (CVSS 9.8) Deserialization of Untrusted Data vulnerability in rmccue/requests. A fix is available for rmccue/requests — see the affected versions and patch details below.
Insecure Deserialization of untrusted data in rmccue/requests
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-29476 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
rmccue/requestsReal-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
Impact
Unserialization of untrusted data.
Patches
The issue has been patched and users of Requests 1.6.0, 1.6.1 and 1.7.0 should update to version 1.8.0.
References
Publications about the vulnerability:
- https://dannewitz.ninja/posts/php-unserialize-object-injection-yet-another-stars-rating-wordpress
- https://github.com/ambionics/phpggc/issues/52
- https://blog.detectify.com/2019/07/23/improving-wordpress-plugin-security/
- https://i.blackhat.com/us-18/Thu-August-9/us-18-Thomas-Its-A-PHP-Unserialization-Vulnerability-Jim-But-Not-As-We-Know-It.pdf
- https://cdn2.hubspot.net/hubfs/3853213/us-18-Thomas-It%27s-A-PHP-Unserialization-Vulnerability-Jim-But-Not-As-We-....pdf
- https://2018.zeronights.ru/wp-content/uploads/materials/9%20ZN2018%20WV%20-%20PHP%20unserialize.pdf
- https://medium.com/@knownsec404team/extend-the-attack-surface-of-php-deserialization-vulnerability-via-phar-d6455c6a1066#3c0f
Originally fixed in WordPress 5.5.2:
- https://github.com/WordPress/wordpress-develop/commit/add6bedf3a53b647d0ebda2970057912d3cd79d3
- https://wordpress.org/news/2020/10/wordpress-5-5-2-security-and-maintenance-release/
Related Security Advisories:
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=2020-28032
- https://nvd.nist.gov/vuln/detail/CVE-2020-28032
Notification to the Requests repo including a fix in:
For more information
If you have any questions or comments about this advisory:
- Open an issue in Request
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | rmccue/requests | ≥ 1.6.0&&< 1.8.0 | 1.8.0composer require rmccue/requests:^1.8.0 |
Affected Products
requestswordpressDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rmccue/requests, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update rmccue/requests to 1.8.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-29476 is resolved across your whole dependency graph.
Workarounds
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.
Frequently Asked Questions
Is CVE-2021-29476 in your dependencies?
Find it across Packagist, including transitive dependencies.