VulnerabilityPublished 13 Nov 2026

CVE-2026-126354: Mikutter · Addressable URI normalization resolves some dotted path segments to the wrong path

Affects mikutterSource GCVE Database

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Authoritative record:CVE-2026-126354· Medium 4.8

Not known to be exploited · CVSS 4.8 Medium · fixed in 2.9.1 : update mikutter when convenient.

Data as of 13 Nov 2026, 21:02 UTC

CVSS 3.1 base score

4.8Medium

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 3.1	4.8

Patch: Available – fixed in 2.9.1

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

Attack Vector: Network
Attack Complexity: High
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 12 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 13 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.

What to do

Affected software

Product	Affected	Fixed in
Homebrewmikutter`pkg:brew/mikutter`Other threats	Affected >=3.4.6	Fixed in–

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Description

### Summary `Addressable::URI.normalize_path` resolves some paths containing `..` segments to a different path than RFC 3986 does. When a path climbs above the root before any other `..` is resolved, the segments that later `..` segments should remove are instead kept: `/../../public/x/../../secret` normalizes to `/public/x/secret` instead of `/secret`. `URI#normalize`, `URI#join`, `URI#==` and `URI#===` all use this normalization. An application that checks a normalized Addressable path against an allowlist, but sends the original URI to something that resolves it according to RFC 3986, can be made to allow a request for a path outside the allowlist. ### Details `normalize_path` in 2.9.0 (`lib/addressable/uri.rb`) removes dot segments by repeating a set of rewrites until nothing changes. On each pass it finds the first `/segment/../` pair with `RULE_2B_2C`, then replaces every textual copy of that pair in the path with `/`: ```ruby pair = normalized_path.match(RULE_2B_2C) ... regexp = "/#{Regexp.escape(parent.to_s)}/\\.\\./|" regexp += "(/#{Regexp.escape(current.to_s)}/\\.\\.$)" ... mod ||= normalized_path.gsub!(Regexp.new(regexp), SLASH) ``` When the first pair found is `/../../`, where the "segment" is itself `..`, every `/../../` in the path is replaced with `/`. That includes copies later in the path, where each `..` should have removed the segment before it. For `/../../public/x/../../secret`: - RFC 3986 §5.2.4 drops the two leading `..` segments, which can't go above the root, then removes `x` and `public`, giving `/secret`. - 2.9.0 replaces both copies of `/../../` with `/` in one step, giving `/public/x/secret`. Paths where an ordinary `/segment/../` pair comes first, such as `/a/../../b/c/../../d`, are resolved correctly. This was introduced in 2.2.5. Versions 2.0.0 through 2.2.4 and earlier versions resolve these paths correctly. It is fixed in 2.9.1, which replaces the rewrite loop with a single pass that correctly follows RFC 3986 §5.2.4. ### Proof of concept ```ruby require "addressable/uri" require "uri" url = "http://example.com/../../public/x/../../secret" # Addressable's normalized path, compared with RFC 3986 resolution by Ruby's URI library puts Addressable::URI.parse(url).normalize.path puts URI.join("http://example.com/", "../../public/x/../../secret").path # join and == use the same normalization puts Addressable::URI.join("http://example.com/", "../../public/x/../../secret").path puts Addressable::URI.parse(url) == Addressable::URI.parse("http://example.com/public/x/secret") # An allowlist check on the normalized path passes, but the request reaches /secret def allowed?(url) = Addressable::URI.parse(url).normalize.path.start_with?("/public/") puts allowed?(url) ``` Output with Addressable 2.9.0: ``` /public/x/secret /secret /public/x/secret true true ``` Output with Addressable 2.9.1: ``` /secret /secret /secret false false ``` ### Impact This is an interpretation conflict (CWE-436) between Addressable and other RFC 3986 resolvers, which could lead to path traversal past an allowlist (CWE-22). An application is affected when it does both of these: - makes an access decision on a path normalized or joined by Addressable, such as "only paths under `/public/` may be proxied" or "only these redirect targets are allowed"; - sends the original, unnormalized URI to a component that resolves dot segments itself, such as an HTTP client, a proxy, a web server or a browser. An attacker may be able to bypass a check by exploiting behavioral differences between URI parsers. Impact from this is application-dependent. Applications that use Addressable's normalized form for both the check and the request are unaffected, as are applications that reject paths containing `..` segments. As a work-around for unpatched versions, before making access decisions on a path, either reject any containing `..` segments, including percent-encoded forms such as `%2e%2e`, or use the same normalized value for both the check and the request.

References

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