Vulnerability · Published Apr 24, 2026 · Assigned by GitHub_M

CVE-2026-41316ERB has an @_init deserialization guard bypass via def_module / def_method / def_class

High 8.1

In plain English

A high-severity unsafe deserialization in erb from ruby. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.1% (higher than 67% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.1High
Exploit odds (30 days)1.1%top 33.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
AlmaLinux:8ruby3.3.10-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9ruby3.0.7-166.el9_7ALSA-2026:18039
AlmaLinux:9ruby4.0.3-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:9ruby3.3.10-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:8ruby-bundled-gems3.3.10-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9ruby-bundled-gems4.0.3-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:9ruby-bundled-gems3.3.10-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:10ruby-default-gems3.3.10-12.el10_1ALSA-2026:18065
AlmaLinux:8ruby-default-gems3.3.10-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9ruby-default-gems4.0.3-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:9ruby-default-gems3.0.7-166.el9_7ALSA-2026:18039
AlmaLinux:9ruby-default-gems3.3.10-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:8ruby-devel3.3.10-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9ruby-devel3.3.10-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:9ruby-devel4.0.3-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:9ruby-devel3.0.7-166.el9_7ALSA-2026:18039
AlmaLinux:10ruby-doc3.3.10-12.el10_1ALSA-2026:18065
AlmaLinux:8ruby-doc3.3.10-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9ruby-doc3.3.10-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:9ruby-doc4.0.3-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:9ruby-doc3.0.7-166.el9_7ALSA-2026:18039
AlmaLinux:8ruby-libs3.3.10-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9ruby-libs3.3.10-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:9ruby-libs3.0.7-166.el9_7ALSA-2026:18039
AlmaLinux:9ruby-libs4.0.3-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:10ruby4.04.0.3-34.el10_2ALSA-2026:20606
AlmaLinux:10ruby4.0-devel4.0.3-34.el10_2ALSA-2026:20606
AlmaLinux:10ruby4.0-doc4.0.3-34.el10_2ALSA-2026:20606
AlmaLinux:10ruby4.0-rubygem-mysql20.5.7-34.el10_2ALSA-2026:20606
AlmaLinux:10ruby4.0-rubygem-pg1.6.3-34.el10_2ALSA-2026:20606
AlmaLinux:8rubygem-abrt0.4.0-1.module_el8.10.0+3799+191214ccALSA-2026:20614
AlmaLinux:8rubygem-abrt-doc0.4.0-1.module_el8.10.0+3799+191214ccALSA-2026:20614
AlmaLinux:8rubygem-bigdecimal3.1.5-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9rubygem-bigdecimal4.0.1-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:9rubygem-bigdecimal3.0.0-166.el9_7ALSA-2026:18039
AlmaLinux:9rubygem-bigdecimal3.1.5-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:10rubygem-bundler2.5.22-12.el10_1ALSA-2026:18065
AlmaLinux:8rubygem-bundler2.5.22-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9rubygem-bundler2.5.22-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:9rubygem-bundler4.0.6-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:9rubygem-bundler2.2.33-166.el9_7ALSA-2026:18039
AlmaLinux:8rubygem-io-console0.7.1-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9rubygem-io-console0.7.1-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:9rubygem-io-console0.5.7-166.el9_7ALSA-2026:18039
AlmaLinux:9rubygem-io-console0.8.2-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:10rubygem-irb1.13.1-12.el10_1ALSA-2026:18065
AlmaLinux:8rubygem-irb1.13.1-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9rubygem-irb1.16.0-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:9rubygem-irb1.3.5-166.el9_7ALSA-2026:18039
AlmaLinux:9rubygem-irb1.13.1-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:8rubygem-json2.7.2-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9rubygem-json2.7.2-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:9rubygem-json2.5.1-166.el9_7ALSA-2026:18039
AlmaLinux:9rubygem-json2.18.0-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:10rubygem-minitest5.20.0-12.el10_1ALSA-2026:18065
AlmaLinux:8rubygem-minitest5.20.0-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9rubygem-minitest6.0.0-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:9rubygem-minitest5.20.0-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:9rubygem-minitest5.14.2-166.el9_7ALSA-2026:18039
AlmaLinux:8rubygem-mysql20.5.5-1.module_el8.10.0+3799+191214ccALSA-2026:20614
AlmaLinux:9rubygem-mysql20.5.5-3.module_el9.7.0+184+e2e36072ALSA-2026:18030
AlmaLinux:9rubygem-mysql20.5.7-1.module_el9.8.0+232+50f6dd36ALSA-2026:20596
AlmaLinux:8rubygem-mysql2-doc0.5.5-1.module_el8.10.0+3799+191214ccALSA-2026:20614
AlmaLinux:9rubygem-mysql2-doc0.5.5-3.module_el9.7.0+184+e2e36072ALSA-2026:18030
AlmaLinux:9rubygem-mysql2-doc0.5.7-1.module_el9.8.0+232+50f6dd36ALSA-2026:20596
AlmaLinux:8rubygem-pg1.5.4-1.module_el8.10.0+3799+191214ccALSA-2026:20614
AlmaLinux:9rubygem-pg1.5.4-2.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:9rubygem-pg1.6.3-1.module_el9.8.0+232+50f6dd36ALSA-2026:20596
AlmaLinux:8rubygem-pg-doc1.5.4-1.module_el8.10.0+3799+191214ccALSA-2026:20614
AlmaLinux:9rubygem-pg-doc1.5.4-2.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:9rubygem-pg-doc1.6.3-1.module_el9.8.0+232+50f6dd36ALSA-2026:20596
AlmaLinux:10rubygem-power_assert2.0.3-12.el10_1ALSA-2026:18065
AlmaLinux:8rubygem-power_assert2.0.3-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9rubygem-power_assert1.2.1-166.el9_7ALSA-2026:18039
AlmaLinux:9rubygem-power_assert3.0.1-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:9rubygem-power_assert2.0.3-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:8rubygem-psych5.1.2-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9rubygem-psych3.3.2-166.el9_7ALSA-2026:18039
AlmaLinux:9rubygem-psych5.1.2-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:9rubygem-psych5.3.1-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:8rubygem-racc1.7.3-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9rubygem-racc1.8.1-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:9rubygem-racc1.7.3-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:10rubygem-rake13.1.0-12.el10_1ALSA-2026:18065
AlmaLinux:8rubygem-rake13.1.0-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9rubygem-rake13.0.3-166.el9_7ALSA-2026:18039
AlmaLinux:9rubygem-rake13.3.1-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:9rubygem-rake13.1.0-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:8rubygem-rbs3.4.0-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9rubygem-rbs3.10.0-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:9rubygem-rbs1.4.0-166.el9_7ALSA-2026:18039
AlmaLinux:9rubygem-rbs3.4.0-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:10rubygem-rdoc6.6.3.1-12.el10_1ALSA-2026:18065
AlmaLinux:8rubygem-rdoc6.6.3.1-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9rubygem-rdoc6.3.4.1-166.el9_7ALSA-2026:18039
AlmaLinux:9rubygem-rdoc6.6.3.1-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:9rubygem-rdoc7.0.3-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:10rubygem-rexml3.4.4-12.el10_1ALSA-2026:18065
AlmaLinux:8rubygem-rexml3.4.4-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9rubygem-rexml3.2.5-166.el9_7ALSA-2026:18039
AlmaLinux:9rubygem-rexml3.4.4-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:9rubygem-rexml3.4.4-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:10rubygem-rss0.3.1-12.el10_1ALSA-2026:18065
AlmaLinux:8rubygem-rss0.3.1-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9rubygem-rss0.2.9-166.el9_7ALSA-2026:18039
AlmaLinux:9rubygem-rss0.3.2-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:9rubygem-rss0.3.1-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:10rubygem-test-unit3.6.1-12.el10_1ALSA-2026:18065
AlmaLinux:8rubygem-test-unit3.6.1-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9rubygem-test-unit3.7.5-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:9rubygem-test-unit3.3.7-166.el9_7ALSA-2026:18039
AlmaLinux:9rubygem-test-unit3.6.1-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:10rubygem-typeprof0.21.9-12.el10_1ALSA-2026:18065
AlmaLinux:8rubygem-typeprof0.21.9-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9rubygem-typeprof0.21.9-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:9rubygem-typeprof0.15.2-166.el9_7ALSA-2026:18039
AlmaLinux:9rubygem-typeprof0.31.1-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:10rubygems3.5.22-12.el10_1ALSA-2026:18065
AlmaLinux:8rubygems3.5.22-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9rubygems3.2.33-166.el9_7ALSA-2026:18039
AlmaLinux:9rubygems3.5.22-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:9rubygems4.0.6-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:10rubygems-devel3.5.22-12.el10_1ALSA-2026:18065
AlmaLinux:8rubygems-devel3.5.22-6.module_el8.10.0+4183+69a3c42fALSA-2026:20614
AlmaLinux:9rubygems-devel4.0.6-32.module_el9.8.0+251+5fdbd96bALSA-2026:20596
AlmaLinux:9rubygems-devel3.5.22-6.module_el9.7.0+245+447713a2ALSA-2026:18030
AlmaLinux:9rubygems-devel3.2.33-166.el9_7ALSA-2026:18039
Alpine:v3.21ruby3.3.13-r0ALPINE-CVE-2026-41316
Debian:12ruby3.1no fix listedDEBIAN-CVE-2026-41316
Debian:13ruby3.3no fix listedDEBIAN-CVE-2026-41316
Debian:14ruby3.3no fix listedDEBIAN-CVE-2026-41316
Rocky Linux:10ruby0:3.3.10-12.el10_1RLSA-2026:18065
Rocky Linux:9ruby0:3.0.7-166.el9_7RLSA-2026:18039
Rocky Linux:10ruby4.00:4.0.3-34.el10_2RLSA-2026:20606
Rocky Linux:8rubygem-abrt0:0.4.0-1.module+el8.10.0+1826+b62220b4RLSA-2026:20614
Rocky Linux:8rubygem-abrt0:0.4.0-1.module+el8.5.0+668+665814faRLSA-2026:20614
Rocky Linux:8rubygem-abrt0:0.4.0-1.module+el8.10.0+1827+16ecb9d2RLSA-2026:20614
Rocky Linux:8rubygem-abrt0:0.4.0-1.module+el8.9.0+1537+0b2034bdRLSA-2026:20614
Rocky Linux:8rubygem-abrt0:0.4.0-1.module+el8.10.0+1741+bdb5b6caRLSA-2026:20614
Rocky Linux:8rubygem-abrt0:0.4.0-1.module+el8.10.0+1679+61871737RLSA-2026:20614
Rocky Linux:8rubygem-abrt0:0.4.0-1.module+el8.10.0+1820+f3fffb92RLSA-2026:20614
Rocky Linux:8rubygem-mysql20:0.5.5-1.module+el8.10.0+1679+61871737RLSA-2026:20614
Rocky Linux:8rubygem-mysql20:0.5.5-1.module+el8.10.0+1827+16ecb9d2RLSA-2026:20614
Rocky Linux:9rubygem-mysql20:0.5.5-3.module+el9.7.0+40032+36e56d0dRLSA-2026:18030
Rocky Linux:9rubygem-mysql20:0.5.7-1.module+el9.8.0+40094+ce01217cRLSA-2026:20596
Rocky Linux:8rubygem-pg0:1.5.4-1.module+el8.10.0+1679+61871737RLSA-2026:20614
Rocky Linux:8rubygem-pg0:1.5.4-1.module+el8.10.0+1827+16ecb9d2RLSA-2026:20614
Rocky Linux:9rubygem-pg0:1.6.3-1.module+el9.8.0+40094+ce01217cRLSA-2026:20596
RubyGemserb4.0.4.1GHSA-q339-8rmv-2mhv
RubyGemserb4.0.3.1GHSA-q339-8rmv-2mhv
RubyGemserb6.0.1.1GHSA-q339-8rmv-2mhv
RubyGemserb6.0.4GHSA-q339-8rmv-2mhv
Ubuntu:25.10jrubyno fix listedUBUNTU-CVE-2026-41316
Ubuntu:26.04:LTSjrubyno fix listedUBUNTU-CVE-2026-41316
Ubuntu:26.10jrubyno fix listedUBUNTU-CVE-2026-41316
Ubuntu:22.04:LTSruby3.0no fix listedUBUNTU-CVE-2026-41316
Ubuntu:24.04:LTSruby3.2no fix listedUBUNTU-CVE-2026-41316
Ubuntu:25.10ruby3.3no fix listedUBUNTU-CVE-2026-41316
Ubuntu:26.04:LTSruby3.3no fix listedUBUNTU-CVE-2026-41316
Ubuntu:26.10ruby3.3no fix listedUBUNTU-CVE-2026-41316

Affected products (as reported)

VendorProductVersions
ruby erb < 4.0.3.1= 4.0.4>= 5.0.0, < 6.0.1.1>= 6.0.2, < 6.0.4

Weakness: CWE-693, CWE-502 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

References