CVE-2025-61921
Sinatra is vulnerable to ReDoS through ETag header value generation
Impact
### Summary There is a denial of service vulnerability in the `If-Match` and `If-None-Match` header parsing component of Sinatra, if the `etag` method is used when constructing the response and you are using Ruby < 3.2. ### Details Carefully crafted input can cause `If-Match` and `If-None-Match` header parsing in Sinatra to take an unexpected amount of time, possibly resulting in a denial of service attack vector. This header is typically involved in generating the `ETag` header value. Any applications that use the `etag` method when generating a response are impacted if they are using Ruby below version 3.2. ### Resources * https://github.com/sinatra/sinatra/issues/2120 (report) * https://github.com/sinatra/sinatra/pull/2121 (fix) * https://github.com/sinatra/sinatra/pull/1823 (older ReDoS vulnerability) * https://bugs.ruby-lang.org/issues/19104 (fix in Ruby >= 3.2)
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| rubygems | sinatra | < 4.2.0 | 4.2.0 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Sinatrarb | Sinatra | before 4.2.0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://bugs.ruby-lang.org/issues/19104
- https://github.com/sinatra/sinatra/issues/2120
- https://github.com/sinatra/sinatra/pull/1823
- https://github.com/sinatra/sinatra/pull/2121
- https://github.com/sinatra/sinatra/security/advisories/GHSA-mr3q-g2mv-mr4q
- https://github.com/advisories/GHSA-mr3q-g2mv-mr4q
- https://github.com/sinatra/sinatra/commit/3fe8c38dc405586f7ad8f2ac748aa53e9c3615bd
- https://github.com/sinatra/sinatra/commit/8ff496bd4877520599e1479d6efead39304edceb
- https://nvd.nist.gov/vuln/detail/CVE-2025-61921
- https://github.com/rubysec/ruby-advisory-db/blob/master/gems/sinatra/CVE-2025-61921.yml