---
id: "CVE-2026-128237"
page: "https://infrastack.ai/live/CVE-2026-128237"
kind: "vulnerability"
aliases: ["CVE-2026-128237"]
title: "Scapy: oversized BER OID input exhausts CPU and crashes parsing"
severity: "medium"
cvss: 6.9
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["network-tooling", "package", "python", "scapy"]
not_affected_if: ["no-untrusted-ber-input", "scapy-2.8.0-or-later"]
published_at: "2026-11-13T10:18:11+00:00"
first_seen_at: "2026-11-13T10:47:33+00:00"
updated_at: "2026-11-13T10:54:31+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-128237", "first_seen_at": "2026-11-13T10:47:33+00:00"}]
exploit_sources: []
---

# Scapy: oversized BER OID input exhausts CPU and crashes parsing

Link for people: https://infrastack.ai/live/CVE-2026-128237 (this .md is for agents)

Scapy versions before 2.8.0 mishandle ASN.1/BER data with many base-128 continuation bytes in OID arcs. A remote attacker can send such data to consume CPU or crash the process with an uncaught ValueError on Python 3.11 and later.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `pip show scapy` and check whether the version is below `2.8.0`
- Look for projects that parse untrusted BER or SNMP/LDAP-style ASN.1 data with Scapy

## Fix

- Scapy: move to `2.8.0` or later

## Timeline

- 2026-11-13T10:47:33+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-128237

## Documents

- [advisory] Vendor advisory: github.com https://github.com/secdev/scapy/security/advisories/GHSA-xx44-g48m-mjp6
- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/scapy-before-2.8.0-denial-of-service-via-quadratic-ber-oid-decoding

## From the sources

Scapy before 2.8.0 contains a denial of service vulnerability in BER_num_dec() and BERcodec_OID.do_dec() that allows remote attackers to exhaust CPU by supplying oversized OID arcs. Attackers can send ASN.1/BER data with many base-128 continuation bytes to cause quadratic CPU consumption or an uncaught ValueError crash on Python 3.11+.

---

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