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
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| OW2 | ASM | 5.0 – < 9.11 | 9.11 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | asm | 9.11.1-1 | — |
| Debian 13 | asm | No fix yet | — |
| Debian 12 | asm | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | asm | No fix yet | — |
| Ubuntu 26.04 LTS | asm | No fix yet | — |
| Ubuntu 24.04 LTS | asm | No fix yet | — |
| Ubuntu 22.04 LTS | asm | No fix yet | — |
| Ubuntu 20.04 LTS | asm | No fix yet | — |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | asm | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Hardened Images 1 | maven3.9 +1 | 3.9.16-0.4.hum1 | RHSA-2026:83847 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | javapackages-bootstrap | No fix yet | — |
| Azure Linux 3 | objectweb-asm | 9.11.1-1 | — |
Advisories 1
- RHSA-2026:83847 Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update Red Hat Security Advisories (RHSA) · Oct 20, 2026
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