Rack: Rack::Static header_rules bypass via dot-segment normalization mismatch
- Exploited
- No known exploitation
- Fix
- Fixed in 2.2.25, 3.1.23, 3.2.8
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 2.2.25, 3.1.23, 3.2.8.
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 22/100 · provisional
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
Rack, a Ruby web server interface, has a flaw in its Rack::Static component where path-specific header rules can be bypassed. Remotely, without logging in, an attacker can retrieve a known file through dot-segment path tricks and get it without the security headers meant for that path, such as Content-Disposition or Content-Security-Policy; this only affects applications that use path-specific header_rules.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
Rack is a modular Ruby web server interface. Prior to 2.2.25, 3.1.23, and 3.2.8, Rack::Static serves a path after Utils.clean_path_info normalization but evaluates header_rules against a path that is only URL-decoded. An unauthenticated attacker can request a known file through raw or percent-encoded dot segments and receive it without path-specific security headers such as Content-Disposition or Content-Security-Policy. Applications that do not use path-specific header_rules are not affected. This issue is fixed in versions 2.2.25, 3.1.23, and 3.2.8.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure17/25No login or user action needed per the CVSS vector, reachable over the network without a login · Unknown: No advisory context yet
- Reach?/20Unknown. No tracked technology or package matched
- Severity5.3/10CVSS 5.3
- No patch0/5No signal
What would change the score
- Would score about 67 if added to CISA KEV
- Would score about 62 if CISA's SSVC rates exploitation active
- Would score about 27 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: 2.2.25, 3.1.23, 3.2.8.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- rack rack
fixed in 2.2.25; From 3.0 · fixed in 3.1.23; From 3.2 · fixed in 3.2.8
Evidence 4
- Advisory
- Repository
- Repository
- Repository
Corrections
None so far.
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Questions about CVE-2026-125110
Is CVE-2026-125110 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-125110?
rack: before 2.2.25; from 3.0 before 3.1.23; from 3.2 before 3.2.8.Source: cve.now feed data
How do I fix CVE-2026-125110?
Upgrade to a fixed version: 2.2.25, 3.1.23, 3.2.8.Source: cve.now feed data