VulnerabilityPublished 3 Nov 2026

CVE-2026-26961: ruby-rack vulnerabilities

Affects ruby-rackSource GCVE Database

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Mentioned vulnerabilities

Not known to be exploited : upgrade to 3.2.4-1ubuntu1.1 soon.

Data as of 4 Nov 2026, 04:01 UTC

Severity

High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

Patch: Available – fixed in 3.2.4-1ubuntu1.1

Exploitation evidence

Disclosed: evidence found.
CVE published 3 Nov 2026
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 3 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

usn-8989-1

What to do

Upgrade the Ubuntu ruby-rack package to 3.2.4-1ubuntu1.1.

Patches and advisories

ubuntu.com/security/notices/USN-8989-1 (opens in a new tab)

Affected software

Product	Affected	Fixed in
Ubuntu 26.04 LTSruby-rack`pkg:deb/ubuntu/ruby-rack?arch=source&distro=resolute`Other threats	Affected <3.2.4-1ubuntu1.1	Fixed in 3.2.4-1ubuntu1.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch is available and should be applied by updating to ruby-rack version 3.2.4-1ubuntu1.1 as provided by the Ubuntu security notice USN-8989-1. After updating, any applications using Rack must be restarted to apply the fixes. No additional mitigation actions are required beyond applying the official update.

Description

Multiple vulnerabilities were discovered in the Ruby Rack webserver interface affecting header parsing, regular expressions, static file handling, and resource consumption. These issues could allow attackers to bypass security filters, cause denial of service through excessive CPU or disk usage, manipulate header values, exfiltrate data, disclose deployment details, or poison generated links. The vulnerabilities are addressed in the updated package version 3.2.4-1ubuntu1.1.

Impact

The vulnerabilities could enable attackers to bypass network security filters, cause denial of service conditions through excessive CPU or disk resource consumption, manipulate HTTP header values, exfiltrate sensitive files or unintentionally served data, disclose internal deployment details such as filesystem paths and usernames, and poison generated links. These impacts affect the confidentiality, integrity, and availability of applications using vulnerable Rack versions.

Summary

A series of security issues in Ruby Rack were identified, including improper parsing of regular expressions (CVE-2026-26961), incorrect handling of multipart headers (CVE-2026-26962), mishandling of the Forwarded header (CVE-2026-32762), excessive CPU consumption from certain Accept-Encoding values (CVE-2026-34230), exposure of full filesystem paths due to directory path derivation errors (CVE-2026-34763), improper static file path handling leading to potential data exfiltration (CVE-2026-34785), bypass of security-relevant response headers on URL-encoded static paths (CVE-2026-34786), denial of service via unbounded Range header requests (CVE-2026-34826), excessive CPU usage from multipart parameter parsing (CVE-2026-34827), unbounded disk space consumption without Content-Length header (CVE-2026-34829), arbitrary file exfiltration through unescaped X-Accel-Mapping header regular expressions (CVE-2026-34830), denial of service from improper Unicode message handling (CVE-2026-34831), and Host header parsing flaws allowing filter bypass or link poisoning (CVE-2026-34835). These vulnerabilities collectively impact network security filtering, data confidentiality, availability, and application behavior.

References

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