CVE-2026-41316
ERB is a templating system for Ruby. Ruby 2.7.0 (before ERB 2.2.0 was published on rubygems.org) introduced an `@_init` instance variable guard in `ERB#result` and `ERB#run` to prevent code execution when an ERB object is reconstructed via `Marshal.load` (deserialization). However, three other public methods that also evaluate `@src` via `eval()` were not given the same guard: `ERB#def_method`, `ERB#def_module`, and `ERB#def_class`. An attacker who can trigger `Marshal.load` on untrusted data in a Ruby application that has `erb` loaded can use `ERB#def_module` (zero-arg, default parameters) as a code execution sink, bypassing the `@_init` protection entirely. ERB 4.0.3.1, 4.0.4.1, 6.0.1.1, and 6.0.4 patch the issue.
- CVSS 3.1
- 8.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS
- 1.1% chance of exploitation in the next 30 days; higher than 66% of CVEs (scores of 2026-10-26)
- CWEs
- CWE-693, CWE-502
- Published
- Modified
- Record from
- the NVD, synced
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-q339-8rmv-2mhv | RubyGems | erb | <4.0.3.1 | 4.0.3.1 |
| GHSA-q339-8rmv-2mhv | RubyGems | erb | >=4.0.4 <4.0.4.1 | 4.0.4.1 |
| GHSA-q339-8rmv-2mhv | RubyGems | erb | >=5.0.0 <6.0.1.1 | 6.0.1.1 |
| GHSA-q339-8rmv-2mhv | RubyGems | erb | >=6.0.2 <6.0.4 | 6.0.4 |