---
id: CVE-2026-110257
title: >-
  OW2 ASM 5.0 before 9.11 contains an excessive memory allocation vulnerability
  in ClassReader.readBootstrapMethodsAttribute() that sizes an int array from
  num_bootstrap_methods without validating attribute_length
summary: >-
  OW2 ASM 5.0 before 9.11 contains an excessive memory allocation vulnerability
  in ClassReader.readBootstrapMethodsAttribute() that sizes an int array from
  num_bootstrap_methods without validating attribute_length. Attackers can
  supply a c…
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H'
cwe:
  - CWE-789
published: '2026-10-14'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T16:17:41.060'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-110257'
references:
  - url: 'https://asm.ow2.io/versions.html'
    label: disclosure@vulncheck.com
  - url: >-
      https://gitlab.ow2.org/asm/asm/-/blob/ASM_9_10_1/asm/src/main/java/org/objectweb/asm/ClassReader.java#L3497
    label: disclosure@vulncheck.com
  - url: >-
      https://gitlab.ow2.org/asm/asm/-/commit/eb5fa95bb0670eaec2ecf9b8a3a501b48e5a967c
    label: disclosure@vulncheck.com
  - url: 'https://gitlab.ow2.org/asm/asm/-/merge_requests/456'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/ow2-asm-5.0-before-9.11-excessive-memory-allocation-via-bootstrapmethods-attribute
    label: disclosure@vulncheck.com
tags:
  - nvd
ingestedAt: '2026-10-14T15:36:13.996Z'
---

## Overview

OW2 ASM 5.0 before 9.11 contains an excessive memory allocation vulnerability in ClassReader.readBootstrapMethodsAttribute() that sizes an int array from num_bootstrap_methods without validating attribute_length. Attackers can supply a crafted class file of about 100 bytes that forces roughly 2 GB allocation, causing an OutOfMemoryError that crashes the JVM or consuming thread.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.