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CVE-2026-49263· NVD / CVE Program· CNA GitHub_M

Capstone WASM `br_table` instruction-size truncation can cause no-progress disassembly and parser desynchronization

Noroxi assessment

Priority: Monitor (action score 8/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.17% (FIRST EPSS).
  • Someone with local access to the system can trigger it. No account or password is required. No special conditions are required; it is repeatable.
  • Fixed version: capstone (Red Hat:hummingbird:1) 0:5.0.8-0.5.hum1; capstone-devel (Red Hat:hummingbird:1) 0:5.0.8-0.5.hum1; capstone-java (Red Hat:hummingbird:1) 0:5.0.8-0.5.hum1.

Low priority for now. Upgrade to capstone (Red Hat:hummingbird:1) 0:5.0.8-0.5.hum1; capstone-devel (Red Hat:hummingbird:1) 0:5.0.8-0.5.hum1; capstone-java (Red Hat:hummingbird:1) 0:5.0.8-0.5.hum1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

LowCVSS 2.0 · v4.0—No exploit Fix available
Published
Aug 14, 2026
Updated
Sep 18, 2026
EPSS
0.1% · 6th percentile

Report tools

JSON

Action score

8

Monitor

Low priority for now.

CVSS
8 / 40 · 2.0 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
2.0
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • capstone-engine capstone

    • < 6.0.0-Alpha9affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12capstonefrom 0—
Red Hat:hummingbird:1capstonebefore 0:5.0.8-0.5.hum10:5.0.8-0.5.hum1
Red Hat:hummingbird:1capstone-develbefore 0:5.0.8-0.5.hum10:5.0.8-0.5.hum1
Red Hat:hummingbird:1capstone-javabefore 0:5.0.8-0.5.hum10:5.0.8-0.5.hum1
Red Hat:hummingbird:1capstone-staticbefore 0:5.0.8-0.5.hum10:5.0.8-0.5.hum1
Red Hat:hummingbird:1python3-capstonebefore 0:5.0.8-0.5.hum10:5.0.8-0.5.hum1

Same product

capstone-engine: all records

Other highest-scoring records for the same primary product.

  • CVE-2025-68114Capstone doesn't check vsnprintf return in SStream_concat, allows stack buffer underflow and overflow
    39Monitor
  • CVE-2017-6952Integer overflow in the cs_winkernel_malloc function in winkernel_mm.c in Capstone 3.0.4 and earlier allows attackers to cause a denial of s
    35Monitor
  • CVE-2025-67873Capstone doesn't check Skipdata length, leading to cs_insn.bytes heap buffer overflow
    31Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2016-7151May 15, 2019 · Capstone 3.0.4 has an out-of-bounds vulnerability (SEGV caused by a read memory access) in X86_insn_reg_intel in arch/X86/X86Mapping.c.
    22Monitor
  • ← EarlierCVE-2026-47143Jul 21, 2026 · Capstone has a NULL Pointer Dereference with 3DNow! opcodes
    23Monitor
  • Later →CVE-2026-49282Aug 14, 2026 · Capstone M68K and RISCV `cs_insn_name()` invalid IDs can trigger out-of-bounds reads and process crashes
    20Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
red hat:capstone0:5.0.8-0.5.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:capstone-devel0:5.0.8-0.5.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:capstone-java0:5.0.8-0.5.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:capstone-static0:5.0.8-0.5.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:python3-capstone0:5.0.8-0.5.hum1 · Red Hat:hummingbird:1Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • No account or password is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
P
Scope
X

Weakness class (CWE)

CWE-197 · Numeric Truncation Error

CVSS vector

CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

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References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records