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Fencer Vulns
medium 5.9

CVE-2026-82746 json

Ash.update_many/4 atomic path skips resource policy authorization, allowing updates to forbidden records

published 2026-09-01 2 mo ago modified 2026-09-08 2 mo ago also EEF-CVE-2026-82746 , GHSA-j7c9-3fw3-jc64 , EUVD-2026-68951

cvss
5.9
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 6%
public exploits
0
none known

Summary

Missing Authorization vulnerability in ash-project ash allows an actor to update records forbidden by resource policies through the atomic path of Ash.update_many/4.

Ash.update_many/4 runs as a single atomic statement (a data-layer update_many, for example a SQL MERGE) whenever an atomic strategy is used and the data layer supports it. Ash.Actions.Update.UpdateMany (lib/ash/actions/update/update_many.ex) took that path even under authorize?: true without applying the resource's policies, so the statement updated every row matched by primary key regardless of the policy filter that authorization would impose. An actor could therefore update records the policies forbid, such as rows belonging to another actor or tenant. The fix restricts the atomic path to data layers supporting changeset filters when authorizing, authorizes each changeset, and merges the resulting policy filter into each changeset so the statement only touches authorized rows.

This issue affects ash: from 3.29.0 before 3.32.2.

Patch / fix

  • hex ash 3.32.2
  • ash-project ash 3.32.2

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

0.17% chance of exploitation in the next 30 days, higher than 6% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/ash-project/ash/security/advisories/GHSA-j7c9-3fw3-jc64 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 5.9 CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
CNA 4.0 5.9 CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/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

Affected packages

ecosystem package affected fixed in
hex ash
>=3.29.0, <3.32.2
3.32.2

Affected products

  • ash-project ash

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.