Vulnerability · Published Oct 14, 2026 · Assigned by VulnCheck

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

Medium 5.5

In plain English

A medium-severity security flaw in ASM from OW2. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 6% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.5Medium

Exploit odds (30 days)0.2%top 93.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	asm	no fix listed	DEBIAN-CVE-2026-110257
Debian:13	asm	no fix listed	DEBIAN-CVE-2026-110257
Debian:14	asm	9.11.1-1	DEBIAN-CVE-2026-110257
Ubuntu:22.04:LTS	asm	no fix listed	UBUNTU-CVE-2026-110257
Ubuntu:24.04:LTS	asm	no fix listed	UBUNTU-CVE-2026-110257
Ubuntu:26.04:LTS	asm	no fix listed	UBUNTU-CVE-2026-110257
Ubuntu:26.10	asm	no fix listed	UBUNTU-CVE-2026-110257

Affected products (as reported)

Vendor	Product	Versions
OW2	ASM	5.0 – before 9.11

Weakness: CWE-789 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

References

https://gitlab.ow2.org/asm/asm/-/merge_requests/456 patch
https://gitlab.ow2.org/asm/asm/-/commit/eb5fa95bb0670eaec2ecf9b8a3a501b48e5a967c patch
https://gitlab.ow2.org/asm/asm/-/blob/ASM_9_10_1/asm/src/main/java/org/objectweb/asm/ClassReader.java#L3497 technical-description
ASM 9.11 Release Notes release-notes
VulnCheck Advisory: OW2 ASM 5.0 before 9.11 Excessive Memory Allocation via BootstrapMethods Attribute third-party-advisory