Vulnerability in AccessControl (CVE-2026-77401)
Summary
Vulnerability in AccessControl (CVE-2026-77401). Confidential information can be exposed externally. Exploitable via format. Mitigation: upgrade to 7.4 or later.
Original description
The description as published by the source.
Impact
Python's string format functionality allows someone controlling the format string to "read" objects accessible (recursively) via attribute access and subscription from accessible objects. Those attribute accesses and subscriptions use Python's full blown getattr and getitem, not the policy restricted AccessControl variants _getattr_ and _getitem_. This can lead to critical information disclosure.
The AccessControl package already guards against direct access to the formatting functions on string instances, but these mitigations did not cover subclasses of str.
Affected are all users who allow untrusted users to create AccessControl controlled Python code and execute it.
Patches
A fix was published with version 7.4.
Workarounds
There is no workaround.
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-2026-77401 has been found in AccessControl.
Attackers can target a specific entry point like format over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 6.8/10.
What to do: upgrade AccessControl to 7.4 or later.
If unsure, ask your IT team or search "AccessControl CVE-2026-77401" on the vendor's site.
CVE-2026-77401 (AccessControl) — CWE-693 / CVSS v3 6.8
Attack vector: remote (network-reachable) / no user interaction
Attack surface: format / getattr / getitem / AccessControl
Patched: 7.4 — apply immediately
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.
A vulnerability (CWE-693) exists in AccessControl. Attackers reach the vulnerable code path via format.
Check the vendor advisory for the affected versions of AccessControl. Attack surface: format / getattr / getitem / AccessControl.
Severity: Medium (CVSS 6.8/10). Confidential information can be exposed externally.
Update to 7.4.
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 'AccessControl' . 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
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1Identify exposure identify
grep -r 'AccessControl' . | 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
AccessControlを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade AccessControl to 7.4ステージング環境で 7.4 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-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。
Affected packages
References
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- package pypi.org
- web github.com
- web github.com
- web github.com