5

CVE-2026-55244: ASTEVAL: Sandbox Escape via BaseException Subclasses

Deferred
AliasesGHSA-89v8-rhwq-hf77PYSEC-2026-3807UBUNTU-CVE-2026-55244
Published 14-09-2026Last modified 16-09-2026

Vulnerability summary

CVE-2026-55244 is a medium (CVSS 5.0) Uncaught Exception vulnerability in lmfit asteval. EPSS estimates a 0.18% chance of exploitation in the next 30 days, higher than 7.3% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 5, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
5.0/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.18%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 0 · Related 1
CGA-7QJV-JH75-HCJ9

Timeline

  1. 14-09-2026
    PublishedVulnerability first disclosed.
  2. 16-09-2026
    Last modifiedVulnerability information updated.

Description

ASTEVAL is an evaluator of Python expressions and statements. Prior to 1.0.9, FROM_PY in asteval/astutils.py exposes BaseException, SystemExit, KeyboardInterrupt, and GeneratorExit to expressions evaluated by asteval.Interpreter.eval(), while run() and eval() in asteval/asteval.py catch Exception rather than these non-Exception BaseException subclasses. When an attacker-controlled expression raises one of these classes, on_raise() passes the class to raise_exception(), and the resulting exception bypasses the interpreter's safety handlers and propagates into the calling application. A consuming service that evaluates untrusted expressions can therefore be terminated or have signal and cleanup handling disrupted, causing denial of service. The separately documented read-only open() capability is not part of this vulnerability. This issue is fixed in version 1.0.9.

CVSS metrics

7 scores · 7 sources · 1 version

EPSS trend

Probability

0.18%

Chance of exploitation in the next 30 days

Percentile

7%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.18% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: local access, low-privilege account, user interaction (CVSS vector). Other conditions: not stated in public data.

Chainguard3 products
  • checkov< 3.3.16-r2
  • keep-api< 0.54.2-r6
  • keep-api-fips< 0.54.2-r9
Debian1 product
  • python-astevalAll versions (No fix recorded)
Lmfit1 product
Opensuse1 product
  • python-asteval&distro=openSUSE Tumbleweed< 1.0.9-1.1
PyPI1 product
  • asteval< 1.0.9
Ubuntu1 product
  • python-astevalAll versions (No fix recorded)
Wolfi1 product
  • checkov< 3.3.16-r2

7 vendors · 9 products

References

14 links
Show all 14 references