Bug 2516114 (CVE-2026-49263) - CVE-2026-49263 capstone: Capstone: Denial of Service and parser desynchronization via WebAssembly `br_table` instruction-size truncation
Summary: CVE-2026-49263 capstone: Capstone: Denial of Service and parser desynchroniza...
Keywords:
Status: NEW
Alias: CVE-2026-49263
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 2523310 2523311 2523312 2523313 2523314 2523315
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-08-14 18:19 UTC by OSIDB Bzimport
Modified: 2026-08-25 09:24 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:


Attachments (Terms of Use)

Description OSIDB Bzimport 2026-08-14 18:19:38 UTC
Capstone is a disassembly framework. Prior to version 6.0.0-Alpha9, Capstone's WebAssembly backend accepts attacker-controlled raw WASM instruction bytes through the public `cs_disasm()` and `cs_disasm_iter()` APIs. For a large but well-formed `br_table` instruction, the WASM decoder accumulates the immediate length in a wider local variable but returns it through a `uint16_t` instruction-size path. When the encoded instruction length is exactly 65,536 bytes, the size wraps to zero and `cs_disasm()` can repeatedly decode the same instruction without advancing. For larger lengths, `cs_disasm_iter()` advances into the middle of the `br_table` payload and decodes target bytes as subsequent instructions. This is an availability and parser-integrity issue. Version 6.0.0-Alpha9 patches the issue.


Note You need to log in before you can comment on or make changes to this bug.