Vulnerability in asteval (CVE-2026-102734)
Summary
Vulnerability in asteval (CVE-2026-102734). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
Summary
With its default configuration (numpy enabled, import disabled), asteval's Interpreter lets an attacker-controlled expression obtain a raw arbitrary process-memory read and write primitive, without using import, any __dunder__ attribute, or eval/exec/getattr. Arbitrary in-process read/write is equivalent to arbitrary code execution and is a complete escape of the sandbox whose entire purpose is "untrusted string in, no arbitrary execution out." Any application that feeds untrusted input to asteval with numpy installed (the default) is affected.
Details
asteval's attribute filter (asteval/astutils.py: safe_getattr) blocks every __dunder__ name and blocks objects whose attribute value is identity-equal to one of the modules in UNSAFE_MODULES = {io, os, sys, ctypes}. The ctypes module entry was added recently (commit 9d9d430) and correctly blocks ndarray.ctypes._ctypes.
However, the module check is identity-only against the ctypes module. It does not cover ctypes type objects and their metaclass methods, which are reachable through numpy's ndarray.ctypes wrapper using only ordinary (non-dunder) attribute names:
zeros(1, dtype=int32).ctypes.shape._type_ ->
ndarray.ctypes exposes .shape (a ctypes array) whose element type ._type_ is ctypes.c_long. None of ctypes, .shape, ._type_ is a dunder, none is in UNSAFE_ATTRS, and the returned value is a type, not the ctypes module, so safe_getattr p…
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-2026-102734 has been found in asteval.
Risk of unauthorized operations or information disclosure. CVSS score: 5.5/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "asteval CVE-2026-102734" on the vendor's site.
CVE-2026-102734 (asteval) — CWE-693 / CVSS v3 5.5
Attack vector: local / unauthenticated
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 asteval.
Check the vendor advisory for the affected versions of asteval.
Severity: Medium (CVSS 5.5/10). Risk of unauthorized operations or information disclosure.
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 'asteval' . 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 'asteval' . | 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
asteval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。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-102734 python-asteval
- Ubuntu UBUNTU-CVE-2026-102734 python-asteval
References
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com