CVE-2026-82741 (GCVE-0-2026-82741)
Vulnerability from cvelistv5 – Published: 2026-09-01 03:33 – Updated: 2026-09-01 03:33
VLAI
EPSS
VEX
Title
Ash.Type.Union with :map_with_tag does not force the tag on dump, enabling tag confusion
Summary
Improper Validation of Specified Type of Input vulnerability in ash-project ash lets an attacker confuse the stored type tag of an Ash.Type.Union value that uses storage: :map_with_tag, bypassing that member's validation and any tag-based authorization.
For a union with storage: :map_with_tag, each member is identified in storage by a configured tag and tag_value. Ash.Type.Union.dump_to_native/2 (lib/ash/type/union.ex) did not force the configured tag when writing the value, so a tag carried in the submitted value was persisted verbatim. An attacker can therefore store a value whose data belongs to one member but whose tag names a different member. On read the value is re-selected by its tag and treated as the incompatible member (a type confusion), bypassing the real member's constraints and any logic or policy that branches on the union tag. The fix drops any incoming tag and forces the configured tag value on dump.
This issue affects ash: from 2.14.18 before 3.32.2.
Severity
CWE
- CWE-1287 - Improper Validation of Specified Type of Input
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/ash-project/ash/security/advis… | vendor-advisoryrelated |
| https://cna.erlef.org/cves/CVE-2026-82741.html | related |
| https://osv.dev/vulnerability/EEF-CVE-2026-82741 | related |
| https://github.com/ash-project/ash/commit/8dbdaec… | patch |
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| ash-project | ash |
Affected:
2.14.18 , < 3.32.2
(semver)
cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:* |
||
| ash-project | ash |
Affected:
b0bd2d23d979e731610327636f51da4981fcef68 , < 8dbdaecd0f115f52e7c3f9a3e798617d6fbf5f7d
(git)
cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:* |
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{
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"type": "coordinator",
"value": "Jonatan M\u00e4nnchen / EEF"
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{
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"type": "reporter",
"value": "Peter Ullrich"
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"value": "\u003cp\u003eImproper Validation of Specified Type of Input vulnerability in ash-project ash lets an attacker confuse the stored type tag of an \u003ccode\u003eAsh.Type.Union\u003c/code\u003e value that uses \u003ccode\u003estorage: :map_with_tag\u003c/code\u003e, bypassing that member\u0027s validation and any tag-based authorization.\u003c/p\u003e\n\u003cp\u003eFor a union with \u003ccode\u003estorage: :map_with_tag\u003c/code\u003e, each member is identified in storage by a configured \u003ccode\u003etag\u003c/code\u003e and \u003ccode\u003etag_value\u003c/code\u003e. \u003ccode\u003eAsh.Type.Union.dump_to_native/2\u003c/code\u003e (\u003ccode\u003elib/ash/type/union.ex\u003c/code\u003e) did not force the configured tag when writing the value, so a tag carried in the submitted value was persisted verbatim. An attacker can therefore store a value whose data belongs to one member but whose tag names a different member. On read the value is re-selected by its tag and treated as the incompatible member (a type confusion), bypassing the real member\u0027s constraints and any logic or policy that branches on the union tag. The fix drops any incoming tag and forces the configured tag value on dump.\u003c/p\u003e\n\u003cp\u003eThis issue affects ash: from 2.14.18 before 3.32.2.\u003c/p\u003e"
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"value": "Improper Validation of Specified Type of Input vulnerability in ash-project ash lets an attacker confuse the stored type tag of an `Ash.Type.Union` value that uses `storage: :map_with_tag`, bypassing that member\u0027s validation and any tag-based authorization.\n\nFor a union with `storage: :map_with_tag`, each member is identified in storage by a configured `tag` and `tag_value`. `Ash.Type.Union.dump_to_native/2` (`lib/ash/type/union.ex`) did not force the configured tag when writing the value, so a tag carried in the submitted value was persisted verbatim. An attacker can therefore store a value whose data belongs to one member but whose tag names a different member. On read the value is re-selected by its tag and treated as the incompatible member (a type confusion), bypassing the real member\u0027s constraints and any logic or policy that branches on the union tag. The fix drops any incoming tag and forces the configured tag value on dump.\n\nThis issue affects ash: from 2.14.18 before 3.32.2."
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"attackVector": "LOCAL",
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"providerMetadata": {
"dateUpdated": "2026-09-01T03:33:03.442Z",
"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
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"references": [
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"url": "https://github.com/ash-project/ash/security/advisories/GHSA-2mmm-gc86-7jgg"
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"source": {
"discovery": "EXTERNAL"
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"title": "Ash.Type.Union with :map_with_tag does not force the tag on dump, enabling tag confusion"
}
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"datePublished": "2026-09-01T03:33:03.442Z",
"dateReserved": "2026-08-31T00:59:10.002Z",
"dateUpdated": "2026-09-01T03:33:03.442Z",
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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