Authorization Flaw in Apache (CVE-2026-82431)
Summary
Vulnerability in Apache (CVE-2026-82431). Successful exploitation can lead to full system takeover. Exploitable via SimpleACLAuthorizer.
Original description
The description as published by the source.
Description
SimpleACLAuthorizer evaluated the user-level command set by returning early when nimbus.users was empty,
before nimbus.groups was considered. An operator who restricted cluster access by group alone, leaving
nimbus.users unset, therefore received no restriction at all: every authenticated principal was permitted
every user-level operation, including submitTopology, beginFileUpload and getNimbusConf.
docs/SECURITY.md presents nimbus.groups as a supported way to lock down a cluster, so a deployment
following the documentation could believe it was restricted while it was not. The failure is silent; nothing
in the logs or the configuration indicates that the group list is being ignored.
Both lists left empty continues to mean that no restriction is configured, which is the shipped default and
is unchanged.
Mitigation
Upgrade to 3.1.0, where nimbus.groups is evaluated whether or not nimbus.users is set.
Users who cannot upgrade immediately should additionally populate nimbus.users with the intended
principals, since a non-empty user list causes the group list to be evaluated on affected versions.
Operators should review Nimbus access logs for operations by principals outside the intended groups.
Note that after upgrading, a cluster configured with nimbus.groups alone becomes restrictive for the first
time. This includes NimbusClient, which calls getLeader on every connection, so clients outside the
configured groups will begin to be…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-82431 has been found in Apache.
Attackers can target a specific entry point like SimpleACLAuthorizer over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 9.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Apache CVE-2026-82431" on the vendor's site.
CVE-2026-82431 (Apache) — CWE-863 / CVSS v3 9.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: SimpleACLAuthorizer / nimbus.users / nimbus.groups / submitTopology
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Incorrect authorization (CWE-863) exists in Apache. Attackers reach the vulnerable code path via SimpleACLAuthorizer without authentication.
Check the vendor advisory for the affected versions of Apache. Attack surface: SimpleACLAuthorizer / nimbus.users / nimbus.groups / submitTopology.
Severity: Critical (CVSS 9.8/10). Successful exploitation can lead to full system takeover.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Apache' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'Apache' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
Apacheを grep し、稼働しているサービス・バージョンを把握する。 -
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
References
- web lists.apache.org
- web openwall.com
- web nvd.nist.gov
- web github.com