How severe is CVE-2021-29487?

CVE-2021-29487 has a CVSS score of 7.4/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-29487?

CVE-2021-29487 affects the following packages: october/system (Packagist), october/system (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2021-29487?

Update october/system to 1.0.472 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-29487 is resolved across your whole dependency graph.

How do I detect CVE-2021-29487 in my Packagist dependencies?

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

How do I mitigate CVE-2021-29487 if there is no patch (or I can't update yet)?

Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Is CVE-2021-29487 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-29487 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-29487?

CVE-2021-29487 has an EPSS (Exploit Prediction Scoring System) score of 0.9%, placing it in the 58th 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-2021-29487?

CVE-2021-29487 is classified as Improper Authentication (CWE-287). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-29487 published, and has it been updated?

CVE-2021-29487 was published on August 26, 2021 and was last updated on September 22, 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

HIGH severity

CVE-2021-29487 — system

HIGHFix: octobercms/library@016a297

CVE-2021-29487 is a high-severity (CVSS 7.4) Improper Authentication vulnerability in october/system. A fix is available for october/system — see the affected versions and patch details below.

October CMS auth bypass and account takeover

Also known asGHSA-h76r-vgf3-j6w5

Published

Aug 26, 2021

Updated

Sep 22, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.9%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs58th percentile — riskier than 58% of all scored CVEsHighest risk

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

How urgent is this, really

CVE-2021-29487 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

2 pkgs affected

🐘october/system🐘october/system

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

Impact

An attacker can exploit this vulnerability to bypass authentication using a specially crafted persist cookie.

To exploit this vulnerability, an attacker must obtain a Laravel’s secret key for cookie encryption and signing.
Due to the logic of how this mechanism works, a targeted user account must be logged in while the attacker is exploiting the vulnerability.
Authorization via persist cookie not shown in access logs.

Patches

Issue has been patched in Build 472 and v1.1.5
Shortened patch instructions

Workarounds

Apply https://github.com/octobercms/library/commit/016a297b1bec55d2e53bc889458ed2cb5c3e9374 and https://github.com/octobercms/library/commit/5bd1a28140b825baebe6becd4f7562299d3de3b9 to your installation manually if you are unable to upgrade.

[Update 2022-01-20] Shortened patch instructions can be found here.

Recommendations

We recommend the following steps to make sure your server stays secure:

Keep server OS and system software up to date.
Keep October CMS software up to date.
Use a multi-factor authentication plugin.
Change the default backend URL or block public access to the backend area.
Include the Roave/SecurityAdvisories Composer package to ensure that your application doesn't have installed dependencies with known security vulnerabilities.

References

Bugs found as part of Solar Security CMS Research. Credits to: • Andrey Basarygin • Andrey Guzei • Mikhail Khramenkov • Alexander Sidukov • Maxim Teplykh

For more information

If you have any questions or comments about this advisory:

Email us at [email protected]

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`october/system`	all versions	1.0.472`composer require october/system:^1.0.472`
🐘Packagist	`october/system`	≥ 1.1.1&&< 1.1.5	1.1.5`composer require october/system:^1.1.5`

Affected Products

1 product · 2 configurations

Application

octoberoctobercms

≥ 1.1.1 && < 1.1.5

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for october/system, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update october/system to 1.0.472 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-29487 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

### Impact An attacker can exploit this vulnerability to bypass authentication using a specially crafted persist cookie. - To exploit this vulnerability, an attacker must obtain a Laravel’s secret key for cookie encryption and signing. - Due to the logic of how this mechanism works, a targeted user account must be logged in while the attacker is exploiting the vulnerability. - Authorization via persist cookie not shown in access logs. ### Patches - Issue has been patched in Build 472 and v1.1.5 - [Shortened patch instructions](https://github.com/daftspunk/CVE-2021-32648) ### Workarounds