How severe is CVE-2020-15128?

CVE-2020-15128 has a CVSS score of 6.3/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2020-15128?

CVE-2020-15128 affects the following packages: october/rain (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2020-15128?

Update october/rain to 1.0.468 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-15128 is resolved across your whole dependency graph.

How do I detect CVE-2020-15128 in my Packagist dependencies?

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

How do I mitigate CVE-2020-15128 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2020-15128 actively exploited in the wild?

No public exploit code has been indexed for CVE-2020-15128 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-2020-15128?

CVE-2020-15128 has an EPSS (Exploit Prediction Scoring System) score of 0.7%, placing it in the 53th 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-2020-15128?

CVE-2020-15128 is classified as CWE-565 (CWE-565), Broken Cryptographic Algorithm (CWE-327). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2020-15128 published, and has it been updated?

CVE-2020-15128 was published on July 31, 2020 and was last updated on October 24, 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-2020-15128 — rain

MEDIUMFix: octobercms/library@28310d4

CVE-2020-15128 is a medium-severity (CVSS 6.3) CWE-565 vulnerability in october/rain. A fix is available for october/rain — see the affected versions and patch details below.

Reliance on Cookies without validation in OctoberCMS

Also known asGHSA-55mm-5399-7r63

Published

Jul 31, 2020

Updated

Oct 24, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 2, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.7%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs53th percentile — riskier than 53% of all scored CVEsHighest risk

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

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐘october/rain

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

Previously encrypted cookie values were not tied to the name of the cookie the value belonged to. This meant that certain classes of attacks that took advantage of other theoretical vulnerabilities in user facing code (nothing exploitable in the core project itself) had a higher chance of succeeding.

Specifically, if your usage exposed a way for users to provide unfiltered user input and have it returned to them as an encrypted cookie (ex. storing a user provided search query in a cookie) they could then use the generated cookie in place of other more tightly controlled cookies; or if your usage exposed the plaintext version of an encrypted cookie at any point to the user they could theoretically provide encrypted content from your application back to it as an encrypted cookie and force the framework to decrypt it for them.

Patches

Issue has been patched in Build 468 (v1.0.468).

NOTE: If you are using the cookie session driver, all of your session data will be invalidated. All other session drivers should smoothly upgrade to the changes (although the backend authentication persist cookie will also be invalidated requiring users to login again once their current session expires).

Workarounds

Apply https://github.com/octobercms/library/commit/28310d4fb336a1741b39498f4474497644a6875c to your installation manually if unable to upgrade to Build 468.

References

For more information

If you have any questions or comments about this advisory:

Email us at [email protected]

Threat Assessment

Assessed as Low given that it is not directly exploitable within the core but requires other security vulnerabilities within the application to have an effect and the severity of its effect depends entirely on the severity of those other holes in the application's defences.

Acknowledgements

Thanks to Takashi Terada of Mitsui Bussan Secure Directions, Inc. for finding the original issue in Laravel and @taylorotwell for sharing the report with the October CMS team.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`october/rain`	≥ 1.0.319&&< 1.0.468	1.0.468`composer require october/rain:^1.0.468`

Affected Products

1 product · 1 configurations

Application

octoberoctobercms

< 1.0.468

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/rain, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update october/rain to 1.0.468 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-15128 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### Impact Previously encrypted cookie values were not tied to the name of the cookie the value belonged to. This meant that certain classes of attacks that took advantage of other theoretical vulnerabilities in user facing code (nothing exploitable in the core project itself) had a higher chance of succeeding. Specifically, if your usage exposed a way for users to provide unfiltered user input and have it returned to them as an encrypted cookie (ex. storing a user provided search query in a cookie) they could then use the generated cookie in place of other more tightly controlled cookies; o