🛡️ CVE-2021-41817 — date
Description
Regular expression denial of service vulnerability (ReDoS) in date
Date’s parsing methods including Date.parse are using Regexps internally, some of which are vulnerable against regular expression denial of service. Applications and libraries that apply such methods to untrusted input may be affected.
The fix limits the input length up to 128 bytes by default instead of changing the regexps. This is because Date gem uses many Regexps and it is possible that there are still undiscovered vulnerable Regexps. For compatibility, it is allowed to remove the limitation by explicitly passing limit keywords as nil like Date.parse(str, limit: nil), but note that it may take a long time to parse.
Please update the date gem to version 3.2.1, 3.1.2, 3.0.2, and 2.0.1, or later. You can use gem update date to update it. If you are using bundler, please add gem "date", ">= 3.2.1" to your Gemfile. If you import date from the standard library rather than as a gem you should update your Ruby install to 3.0.3, 2.7.5, 2.6.9 or later.
Users unable to upgrade may consider using Date.strptime instead with a predefined date format
```ruby
Date.strptime('2001-02-20', '%Y-%m-%d')
```
How this vulnerability can be exploited
This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.
Weakness class
CVE-2021-41817 is classified as CWE-1333: Inefficient Regular Expression Complexity. A regular expression backtracks catastrophically on crafted input, consuming CPU out of proportion to input size.
Affected software
CVE-2021-41817 is recorded against 3 packages.
- date (fixed in 2.0.1)
- ruby
- ruby-min
Timeline and source
Published on 16 November 2021 and last revised on 27 January 2025. No public exploit is currently recorded for this entry. Record sourced from OSV.
References
nvd.nist.gov (Advisory)
github.com (Web)
hackerone.com (Web)
github.com (Package)
github.com (Web)
lists.fedoraproject.org (Web)
lists.fedoraproject.org (Web)
lists.fedoraproject.org (Web)
lists.fedoraproject.org (Web)
security.gentoo.org (Web)
www.ruby-lang.org (Web)
CVE-2021-41817 on other distributions
Each distribution ships its own build and its own fixed version. Pick the one you run:
Details
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| date | — | 2.0.1 |
| ruby | — | — |
| ruby-min | — | — |
References
Similar Threats
- Unknown MAL-2025-43944
- Unknown MAL-2025-18010
- Unknown MAL-2025-18011
- Unknown MAL-2025-18012
- Unknown MAL-2025-18013
More CVE 2021 advisories
Browse all of CVE 2021 in the advisory index.
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