VulnerabilityPublished 12 Nov 2026

CVE-2026-126208: Loofah · SVG `<textPath>` and `<mpath>` bypass local-reference restriction

Affects loofahSource GCVE Database

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Authoritative record:CVE-2026-126208· Medium 4.7

Not known to be exploited · CVSS 4.7 Medium : upgrade to 2.25.3 when convenient.

Data as of 12 Nov 2026, 22:37 UTC

CVSS 3.1 base score

4.7Medium

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	4.7

Patch: Available – fixed in 2.25.3

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Changed
Confidentiality: Low
Integrity: None
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: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
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: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
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: None: There is no loss of integrity within 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 12 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

Upgrade loofah to 2.25.3.

Affected software

Product	Affected	Fixed in
RubyGemsloofah	Affected <2.25.3	Fixed in 2.25.3

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

AI-suggested

Upgrade Loofah to version 2.25.3 or later, which fixes the issue by correctly restricting external references on <textPath> and <mpath> elements. Applications using rails-html-sanitizer should also update to versions that include this fix. No additional mitigation is required as the fix fully addresses the vulnerability.

Description

Loofah versions prior to 2.25.3 improperly restrict local references in SVG elements <textPath> and <mpath>, allowing external URLs to bypass sanitization. This causes Firefox to fetch attacker-controlled URLs when rendering sanitized SVG content, leaking the viewer's IP address, user agent, and referrer. Chrome and WebKit are not affected by this fetch behavior. The vulnerability affects applications using Loofah's default allowlist or rails-html-sanitizer permitting SVG elements. A fix is available in Loofah 2.25.3.

Impact

The vulnerability allows external URLs in <textPath> and <mpath> SVG elements to bypass sanitization and be fetched by Firefox when rendering the content. This results in leakage of the viewer's IP address, user agent, and referrer to attacker-controlled servers. Additionally, the attacker can cause requests to hosts accessible only from the viewer's network. There is no script execution or direct code injection risk. Chrome and WebKit browsers do not fetch these external references, limiting the impact to Firefox users. Applications sanitizing user-supplied SVG with affected Loofah versions or rails-html-sanitizer configurations permitting SVG are vulnerable.

Summary

Loofah's sanitization restricts href and xlink:href attributes on certain SVG elements to same-document references to prevent external resource loading. However, the <textPath> element was listed in lowercase ('textpath') in the safelist, which does not match the HTML5 parser's 'textPath' casing, causing the restriction to fail. The <mpath> element was missing from the safelist entirely, so its references were unrestricted. As a result, external URLs in these elements survive sanitization. Firefox fetches these external references during rendering, leaking network information to the attacker. Chrome and WebKit do not perform these fetches. The rails-html-sanitizer gem, which reuses Loofah's safelist, is also affected. The issue is fixed in Loofah version 2.25.3.

CWE-178Improper Handling of Case Sensitivity (opens in a new tab)
Base weakness
The product does not properly account for differences in case sensitivity when accessing or determining the properties of a resource, leading to inconsistent results.
Architecture and Design · Input Validation
Avoid making decisions based on names of resources (e.g. files) if those resources can have alternate names.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Implementation · Input Validation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174).
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-184Incomplete List of Disallowed Inputs (opens in a new tab)
Base weaknessOWASP Top 10 A03:2021: Injection (opens in a new tab)
The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are not allowed by policy or otherwise require other action to neutralize before additional processing takes place, but the list is incomplete.
Implementation · Input Validation
Do not rely exclusively on detecting disallowed inputs. There are too many variants to encode a character, especially when different environments are used, so there is a high likelihood of missing some variants. Only use detection of disallowed inputs as a mechanism for detecting suspicious activity.
Attack patterns
Double Encoding (opens in a new tab)
Command Delimiters (opens in a new tab)
Flash Injection (opens in a new tab)
Using Leading 'Ghost' Character Sequences to Bypass Input Filters (opens in a new tab)
Exploiting Multiple Input Interpretation Layers (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 12 Nov 2026, 22:37 UTC

WeaknessesCWE-178, CWE-184

Technical details

References

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