What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-14 · updated 2026-10-14
• Weakness: CWE-789

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.

Affected products

• OW2 ASM: from 5.0 before 9.11 — fixed in 9.11

How to fix

Upgrade to a fixed version: OW2 ASM 9.11. Check the vendor advisory for mitigations.

References

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

Get alerted when CVE-2026-110257 or the next vulnerability affects your stack