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GHSA-crgc-2583-rw27
No affected components available
Minder engine is susceptible to a denial of service from memory exhaustion that can be triggered from maliciously created templates.
Minder engine uses templating to generate strings for various use cases such as URLs, messages for pull requests, descriptions for advisories. In some cases can the user control both the template and the params for it, and in a subset of these cases, Minder reads the generated template entirely into memory. When Minders templating meets both of these conditions, an attacker is able to generate large enough templates that Minder will exhaust memory and crash.
One of these places is the REST ingester:
https://github.com/stacklok/minder/blob/daccbc12e364e2d407d56b87a13f7bb24cbdb074/internal/engine/ingester/rest/rest.go#L115-L123
With control over both endpoint and retp on the following line:
https://github.com/stacklok/minder/blob/daccbc12e364e2d407d56b87a13f7bb24cbdb074/internal/engine/ingester/rest/rest.go#L121
… an attacker can make Minder generate a large template that Minder reads into memory on the following line by invoking endpoint.String():
https://github.com/stacklok/minder/blob/daccbc12e364e2d407d56b87a13f7bb24cbdb074/internal/engine/ingester/rest/rest.go#L131
Consider this example:
package main
import (
"fmt"
"html/template"
"os"
)
type EndpointTemplateParams struct {
// Params are the parameters to be used in the template
Params map[string]any
}
func main() {
retp := &EndpointTemplateParams{
Params: map[string]any{
"params": make([]string, 10),
},
}
fmt.Println(retp)
const templ = `
{{range $idx, $e := .Params.params}}
loooooooooooooooooooooooooooooooong-string-{{$idx}}
{{end}}
{{range $idx, $e := .Params.params}}
loooooooooooooooooooooooooooooooong-string-{{$idx}}
{{end}}
{{range $idx, $e := .Params.params}}
loooooooooooooooooooooooooooooooong-string-{{$idx}}
{{end}}`
tmpl := template.Must(template.New("").Parse(templ))
if err := tmpl.Execute(os.Stdout, retp); err != nil {
panic(err)
}
}
This example imitates the behavior on these lines:
https://github.com/stacklok/minder/blob/daccbc12e364e2d407d56b87a13f7bb24cbdb074/internal/engine/ingester/rest/rest.go#L115-L123
Running this example generates the following template:
loooooooooooooooooooooooooooooooong-string-0
loooooooooooooooooooooooooooooooong-string-1
loooooooooooooooooooooooooooooooong-string-2
loooooooooooooooooooooooooooooooong-string-3
loooooooooooooooooooooooooooooooong-string-4
loooooooooooooooooooooooooooooooong-string-5
loooooooooooooooooooooooooooooooong-string-6
loooooooooooooooooooooooooooooooong-string-7
loooooooooooooooooooooooooooooooong-string-8
loooooooooooooooooooooooooooooooong-string-9
loooooooooooooooooooooooooooooooong-string-0
loooooooooooooooooooooooooooooooong-string-1
loooooooooooooooooooooooooooooooong-string-2
loooooooooooooooooooooooooooooooong-string-3
loooooooooooooooooooooooooooooooong-string-4
loooooooooooooooooooooooooooooooong-string-5
loooooooooooooooooooooooooooooooong-string-6
loooooooooooooooooooooooooooooooong-string-7
loooooooooooooooooooooooooooooooong-string-8
loooooooooooooooooooooooooooooooong-string-9
loooooooooooooooooooooooooooooooong-string-0
loooooooooooooooooooooooooooooooong-string-1
loooooooooooooooooooooooooooooooong-string-2
loooooooooooooooooooooooooooooooong-string-3
loooooooooooooooooooooooooooooooong-string-4
loooooooooooooooooooooooooooooooong-string-5
loooooooooooooooooooooooooooooooong-string-6
loooooooooooooooooooooooooooooooong-string-7
loooooooooooooooooooooooooooooooong-string-8
loooooooooooooooooooooooooooooooong-string-9
A malicious user can call the loop more times, increase the loop count and/or make the repeated long string longer to make the size of the template bigger.
A sufficiently large template will consume a lot of memory on this line which will exhaust memory on the machine and crash the Minder server:
https://github.com/stacklok/minder/blob/daccbc12e364e2d407d56b87a13f7bb24cbdb074/internal/engine/ingester/rest/rest.go#L121
Minder should enforce a limit to generated templates before reading them into memory.
The following templates are believed to be vulnerable:
https://github.com/stacklok/minder/blob/daccbc12e364e2d407d56b87a13f7bb24cbdb074/internal/engine/ingester/rest/rest.go#L121
https://github.com/stacklok/minder/blob/e7f9914de9af5a69e3e6fe2bdfaaf22e62be42c0/internal/engine/actions/remediate/pull_request/pull_request.go#L199
https://github.com/stacklok/minder/blob/e7f9914de9af5a69e3e6fe2bdfaaf22e62be42c0/internal/engine/actions/remediate/pull_request/pull_request.go#L510
Minder has a few other templates especially in its engine which needs reviewing too. As a default, all templates should be limited in size before Minder reads them into memory.
The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the availability of the system.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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