Arbitrary File Read via Template Injection in Snapshot Patterns

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Template Injection in instance snapshot creation component in Canonical LXD (>= 4.0) allows an attacker with instance configuration permissions to read arbitrary files on the host system via specially crafted snapshot pattern templates using the Pongo2 template engine.

Source published

2 Oct 2025 09:16:02 UTC

Source modified

2 Oct 2025 13:27:42 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 4.0 · 7.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Template Injection in instance snapshot creation component in Canonical LXD (>= 4.0) allows an attacker with instance configuration permissions to read arbitrary files on the host system via specially crafted snapshot pattern templates using the Pongo2 template engine.

Source published

Oct 2, 2025, 9:16:02 AM (timezone not stated)

Source modified

Oct 2, 2025, 1:27:42 PM (timezone not stated)

Observed here

9 Nov 2026 09:15:59 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 4.0 · 7.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Template Injection in instance snapshot creation component in Canonical LXD (>= 4.0) allows an attacker with instance configuration permissions to read arbitrary files on the host system via specially crafted snapshot pattern templates using the Pongo2 template engine.

Source published

2 Oct 2025 10:15:38 UTC

Source modified

12 Oct 2026 15:10:00 UTC

Observed here

25 Oct 2026 02:25:06 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 7.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS 3.1 · [email protected] · Primary · 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

### Impact In LXD's instance snapshot creation functionality, the Pongo2 template engine is used in the `snapshots.pattern` configuration for generating snapshot names. While code execution functionality has not been found in this template engine, it has file reading capabilities, creating a vulnerability that allows arbitrary file reading through template injection attacks. ### Reproduction Steps 1. Log in to LXD-UI with an account that has permissions to modify instance settings 2. Set the following template injection payload in the instance snapshot pattern: ``` {% filter urlencode|slice:":100" %}{% include "/etc/passwd" %}{%endfilter %} ``` Note that the above template uses the Pongo2 template engine's include tag to read system files. It also uses urlencode and slice filters to bypass character count and type restrictions. 3. Set scheduled snapshots to run every minute and wait for snapshot generation 4. Wait about a minute and confirm that file contents can be obtained from the created snapshot name ### Risk The attack requires having configuration change permissions for LXD instances. The attack allows reading arbitrary files accessible with LXD process permissions. This could lead to leakage of the following information: -​ LXD host configuration files (/etc/passwd, /etc/shadow, etc.) -​ LXD database files (containing information about all projects and instances) -​ Configuration files and data of other instances -​ Sensitive information on the host system ### Countermeasures Pongo2 provides mechanisms for sandboxing templates. > Template sandboxing (directory patterns, banned tags/filters) ( https://github.com/flosch/pongo2/tree/master?tab=readme-ov-file#features ) This functionality allows banning specific tags and filters by generating a custom TemplateSet. At minimum, the following tags are considered to pose a risk of file leakage on the LXD host when used. Therefore, banning these can provide countermeasures against file reading attacks. -​ include -​ ssi -​ extends -​ import The deny-list approach is prone to vulnerability recurrence due to missed countermeasures or new feature additions. Therefore, as the safest approach, we recommend using an allow-list format to permit only necessary functions. However, as far as our investigation shows, pongo2 does not have functionality to retrieve a list of registered tags or filters, nor does it provide means to implement an allow-list approach. Therefore, it is necessary to either forcibly obtain the registration list through reflection and ban anything not on the allow-list, or ban everything from the current implemented list since the library has not been updated for about two years. In LXD's implementation, template injection attacks can be prevented by modifying the `RenderTemplate` function in `shared/util.go` to use a restricted `TemplateSet` as shown above. ### Patches | LXD Series | Status | | ------------- | ------------- | | 6 | Fixed in LXD 6.5 | | 5.21 | Fixed in LXD 5.21.4 | | 5.0 | Ignored - Not critical | | 4.0 | Ignored - EOL and not critical | ### References Reported by GMO Flatt Security Inc.

Source published

2 Oct 2025 21:21:33 UTC

Source modified

8 Jul 2026 07:59:26 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Publisher rating · HIGH

Canonical LXD Arbitrary File Read via Template Injection in Snapshot Patterns in github.com/lxc/lxd

Source published

5 Nov 2025 18:41:15 UTC

Source modified

5 Nov 2025 19:57:36 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.