What’s Vulnerable › Vulnerabilities

CVE-2026-110259: OW2 ASM 3.0 before 9.11 Uncontrolled Recursion via ClassWriter.replaceAsmInstructions()

• 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 2026-10-26
• Weakness: CWE-674

Description

OW2 ASM 3.0 before 9.11 contains an uncontrolled recursion vulnerability in ClassWriter.replaceAsmInstructions() that allows attackers to cause denial of service through crafted class files. Attackers can supply a class with a large method containing many long forward jumps, triggering unbounded toByteArray() recursion and a StackOverflowError during transformation.

Affected products

• OW2 ASM: from 3.0 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/ClassWriter.java#L751
• https://gitlab.ow2.org/asm/asm/-/commit/e9aca627c17e1619bcb8059afb43382dac6b275f
• https://gitlab.ow2.org/asm/asm/-/merge_requests/459
• https://www.vulncheck.com/advisories/ow2-asm-3.0-before-9.11-uncontrolled-recursion-via-classwriter-replaceasminstructions

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