CVE-2024-21647: Puma HTTP Request/Response Smuggling vulnerability
Affects pumaSource GCVE Database
Not known to be exploited · CVSS 5.9 Medium : upgrade to 6.4.2 when convenient.
Data as of 31 Oct 2026, 01:16 UTC
Thin evidence
One scorer or none| CNA (GitHub_M) | CVSS 3.1 | 5.9 |
|---|
- Patch
- Available – fixed in 6.4.2, 5.6.8
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 8 Jan 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Upgrade puma to 6.4.2; puma to 5.6.8.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| RubyGemspuma | Affected
| Fixed in
|
| RubyGemspuma | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
### Impact Prior to versions 6.4.2 and 5.6.8, puma exhibited dangerous behavior when parsing chunked transfer encoding bodies. Fixed versions limit the size of chunk extensions. Without this limit, an attacker could cause unbounded resource (CPU, network bandwidth) consumption. ### Patches The vulnerability has been fixed in 6.4.2 and 5.6.8. ### Workarounds No known workarounds. ### References * [HTTP Request Smuggling](https://portswigger.net/web-security/request-smuggling) * Open an issue in [Puma](https://github.com/puma/puma) * See our [security policy](https://github.com/puma/puma/security/policy)
References
- github.com/puma/puma/security/advisories/GHSA-c2f4-cvqm-65w2 (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2024-21647 (opens in a new tab)
- github.com/puma/puma/commit/5fc43d73b6ff193325e657a24ed76dec79133e93 (opens in a new tab)
- github.com/puma/puma/commit/60d5ee3734adc8cee85c3f0561af392448fe19b7 (opens in a new tab)
- github.com/puma/puma/commit/bbb880ffb6debbfdea535b4b3eb2204d49ae151d (opens in a new tab)
- github.com/puma/puma (opens in a new tab)
- github.com/rubysec/ruby-advisory-db/blob/master/gems/puma/CVE-2024-21647.yml (opens in a new tab)
- lists.debian.org/debian-lts-announce/2024/11/msg00004.html (opens in a new tab)