Description
A Regular Expression Denial of Service (ReDoS) issue was discovered in the sanitize_html function of redcloth gem v4.0.0. This vulnerability allows attackers to cause a Denial of Service (DoS) via supplying a crafted payload.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | ruby-redcloth | 4.3.3-1 | — |
| Debian 13 | ruby-redcloth | 4.3.3-1 | — |
| Debian 12 | ruby-redcloth | No fix yet | — |
| Debian 10 | ruby-redcloth | 4.3.2-3+deb10u1 | DLA-3480-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 22.04 LTS | ruby-redcloth | 4.3.2-4ubuntu0.22.04.1 | USN-6358-1 |
| Ubuntu 20.04 LTS | ruby-redcloth | 4.3.2-3+deb10u1build0.20.04.1 | USN-6358-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 18.04 LTS | ruby-redcloth | 4.3.2-3ubuntu0.1~esm1 | USN-6358-1 |
| Ubuntu Pro 16.04 LTS | ruby-redcloth | 4.2.9-5ubuntu0.1~esm1 | USN-6358-1 |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
GitHub 1 repository
-
merbinr/CVE-2023-31606 ★ 2 · Jun 3, 2023
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| RubyGems | RedCloth | < 4.3.3 | 4.3.3 | GHSA-qcm3-vfq5-wfr2 |
Advisories 2
- USN-6358-1 ruby-redcloth vulnerability Ubuntu Security Notices (USN) · Jun 25, 2026
- DLA-3480-1 ruby-redcloth - security update Debian Security (DSA / DLA) · Mar 9, 2026