Low severity · published Aug 14, 2026
CVE-2026-49263
Capstone WASM `br_table` instruction-size truncation can cause no-progress disassembly and parser desynchronization
2.0
CVSS
0.2%
EPSS
No
On KEV
Description
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.
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 7% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CA
capstone · capstone-engine
< 6.0.0-Alpha9 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-49263
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-49263
github.com
https://github.com/capstone-engine/capstone/blob/251c5bb4bc9bb92973e738ae3c5f4ef86f103356/ChangeLog#L102
github.com
https://github.com/capstone-engine/capstone/security/advisories/GHSA-5m9f-vqcm-g5pr
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