CVE
Addressable host spoofing in display_uri via invalid Punycode
- Exploited
- No known exploitation
- Fix
- Fixed in 2.9.1
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 2.9.1.
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- FIRST's estimate of the chance attackers exploit it in the next 30 days, updated daily.What do these mean? →
- 0.27% · 20th percentile
- 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? →
- 21/100 · 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
- Exploitation: none
- Automatable: no
- Technical impact: partial
Summary
Addressable, a Ruby URI library from sporkmonger, can display a misleading host through its display_uri method because its pure-Ruby to_unicode decodes invalid Punycode labels that should be left unchanged. A remote attacker can exploit this without logging in if a user takes an action such as opening the crafted link, causing a trusted-looking host to appear while the real connection still goes to the attacker's host.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
Addressable is an alternative implementation to the URI implementation that is part of Ruby's standard library. From 2.0.0 until 2.9.1, the pure-Ruby Addressable::IDNA.to_unicode implementation decodes invalid Punycode A-labels instead of returning them unchanged. Labels that decode to ASCII text or fail to convert back to the same A-label can therefore make Addressable::URI#display_uri show a trusted-looking host while host, normalized_host, and the connection target retain the attacker-controlled encoded host. A trusted-name comparison using Addressable::IDNA.to_unicode output can also treat two different hosts as the same without displaying the URI. The native libidn implementation, to_ascii, and normalized_host are unaffected. This issue is fixed in version 2.9.1.
cve.now Index
- Exploitation0/40No signal
- Exposure7/25Reachable over the network without a login · Unknown: No advisory context yet
- Reach10/20Affects RubyGems packages
- Severity4.3/10CVSS 4.3
- No patch0/5No signal
What would change the score
- Would score about 76 if added to CISA KEV
- Would score about 71 if CISA's SSVC rates exploitation active
- Would score about 36 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: 2.9.1.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-126348 (Addressable display_uri can show misleading hosts with invalid Punycode A-labels), using the cve.now data below.
Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.
What cve.now has for CVE-2026-126348 (entry last updated 2026-11-13):
Affected:
- sporkmonger addressable: from 2.0.0, fixed in 2.9.1
- RubyGems package addressable: from 2.0.0, fixed in 2.9.1
Fixed versions: 2.9.1.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
CISA KEV: CVE-2026-126348 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-126348 only. If you also check another CVE, look up its own KEV status; never assume it from this one.
How to check:
- Packages (RubyGems): find every lockfile in each project and run the stack.check operation of the cve.now MCP server (execute) on each one. Compare the resolved versions, not the ranges a manifest declares, with the affected versions above. Include transitive dependencies.
Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/sporkmonger/addressable/security/advisories/GHSA-9crm-g4mf-wc5j
- https://github.com/sporkmonger/addressable/commit/b8a59cc0e03f8704f1d7c8122fc8f7ef8548362d
- https://github.com/sporkmonger/addressable/releases/tag/addressable-2.9.1
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.
Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.
Entry: https://cve.now/CVE-2026-126348
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-126348"}.Timeline
- CVE published
- First seen by cve.now1 day
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: partial
- Record last updated
Affected versions
- sporkmonger addressable
From 2.0.0 · fixed in 2.9.1
- addressableRubyGems
From 2.0.0 · fixed in 2.9.1
Evidence 5
Vendor advisory · 1
Establishes: Affected and fixed versions.
- Advisory
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Other links · 2
- Repository
- Repository
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-126348
Is CVE-2026-126348 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-2026-126348?
addressable: from 2.0.0 before 2.9.1. addressable (RubyGems): from 2.0.0 before 2.9.1.Source: cve.now feed data
How do I fix CVE-2026-126348?
Upgrade to a fixed version: 2.9.1.Source: cve.now feed data