CVSS 3.1
7.5 highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HCVE-2026-125111
High (7.5) in rack rack. EPSS 0.4% estimated probability of exploitation activity in the next 30 days.
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Rack is a modular Ruby web server interface. Prior to 2.2.25, 3.1.23, and 3.2.8, Rack::Multipart::Parser can retain parsed data in its internal StringScanner buffer when reads end inside or immediately after multipart headers. An unauthenticated attacker can align many small parts with rack.multipart.buffer_size boundaries so the buffer grows with the request despite per-field, header, and preamble limits, causing a worker to exhaust memory. The attack requires only a well-formed multipart body and affects applications that parse multipart requests. This issue is fixed in versions 2.2.25, 3.1.23, and 3.2.8.
Severity
- EPSS
- 0.4% estimated probability of exploitation activity in the next 30 days; 31st percentile. Scored 2026-11-10. A forecast for this CVE across the internet, not for your own systems.
- CWE
- CWE-400 Uncontrolled Resource Consumption
- Published
- Assigned by
- GitHub_M (CNA)
- NVD analysis
- Not in the NVD yet
- Record from
- the CVE List, synced
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Explain CVE-2026-125111 for an engineer deciding whether to act. Use https://cve.bz/api/public/cves/CVE-2026-125111?via=ask-ai-copy and https://cve.bz/cve/CVE-2026-125111?via=ask-ai-copy as the source of truth: what is affected and which versions fix it, whether it is in CISA KEV, public exploits, and its EPSS (an internet-wide 30-day estimate of exploitation activity, not a forecast for my systems). If they give no fixed versions, use the CVE record https://cveawg.mitre.org/api/cve/CVE-2026-125111 or the vendor advisory, not third-party mirrors. Tell me how to check whether I am affected and how to verify a fix. Cite the sources and say where they are uncertain.Opens a third-party assistant; its answer is its own, not cve.bz's. The prompt holds only this CVE's id and public links.
Affected
Versions
From the CNA's record in the CVE List.
| Product | Affected |
|---|---|
| rack | < 2.2.25 |
| rack | >= 3.0, < 3.1.23 |
| rack | >= 3.2, < 3.2.8 |
Linux distributions
| Distribution | Release | Package | Fixed in | Advisory |
|---|---|---|---|---|
| Debian | 12, 13 | ruby-rack | no fix listed | DEBIAN-CVE-2026-125111 |
| Debian | 14 | ruby-rack | 3.2.8-1 | DEBIAN-CVE-2026-125111 |
From the distributions' data via OSV.dev: the Debian Security Tracker. Modified: reformatted and linked to CVE records. Credits. On the distributions' own pages: Debian.
Attack patterns (CAPEC)
- CAPEC-147 XML Ping of the Death Likelihood: Low · Severity: Medium
- CAPEC-227 Sustained Client Engagement
- CAPEC-492 Regular Expression Exponential Blowup
The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.