Vulnerability in asteval (CVE-2026-55244)
Summary
Vulnerability in asteval (CVE-2026-55244). Risk of unauthorized operations or information disclosure. Exploitable via SystemExit. Mitigation: upgrade to 1.0.6 or later.
Original description
The description as published by the source.
Summary
An attacker who can supply expressions to asteval.Interpreter.eval() can raise SystemExit,
KeyboardInterrupt, GeneratorExit, or BaseException from inside the sandbox. These
exceptions are subclasses of BaseException but not Exception, so they bypass the
except Exception: safety net in both run() and eval(). The exception propagates
verbatim to the calling application, terminating the process or disrupting signal and
cleanup handlers.
This is distinct from prior vulnerabilities CVE-2025-24359 (format string injection) and
GHSA-vp47-9734-prjw (AST mutation TOCTOU), both fixed in 1.0.6. This vector is present in
all versions including 1.0.6 and current HEAD.
Affected Code
asteval/astutils.py, lines 89–108 — FROM_PY exposes dangerous classes to sandbox users:
FROM_PY = ('ArithmeticError', 'AssertionError', 'AttributeError',
'BaseException', # ← escapes except Exception:
'BufferError', 'BytesWarning',
...
'GeneratorExit', # ← escapes except Exception:
...
'KeyboardInterrupt', # ← escapes except Exception:
...
'SystemExit', # ← escapes except Exception:
...)
asteval/asteval.py, line 322 — run() exception handler:
except Exception: # ← does NOT catch BaseException subclasses
if with_raise and self.expr is not None:
self.raise_exception(…
Source: GitHub Security Advisories (Global) 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-2026-55244 has been found in asteval.
Attackers can target a specific entry point like SystemExit over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.0/10.
What to do: upgrade asteval to 1.0.6 or later.
If unsure, ask your IT team or search "asteval CVE-2026-55244" on the vendor's site.
CVE-2026-55244 (asteval) — CWE-248 / CVSS v3 5.0
Attack vector: local
Attack surface: SystemExit / KeyboardInterrupt / GeneratorExit / BaseException
Patched: 1.0.6 — 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-248) exists in asteval. Attackers reach the vulnerable code path via SystemExit.
Check the vendor advisory for the affected versions of asteval. Attack surface: SystemExit / KeyboardInterrupt / GeneratorExit / BaseException.
Severity: Medium (CVSS 5.0/10). Risk of unauthorized operations or information disclosure.
Update to 1.0.6.
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。 -
2Apply patch patch
Upgrade asteval to 1.0.6ステージング環境で 1.0.6 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。