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Fencer Vulns
medium 6.8

CVE-2026-55894 json

Capstone SH disassembler `sh_disassemble` out-of-bounds read via crafted SH2A bytecode

published 2026-08-20 2 mo ago modified 2026-10-18 21 d ago also EUVD-2026-63669

cvss
6.8
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 9%
public exploits
0
none known

Summary

Capstone is a disassembly framework. In 6.0.0-Alpha9 and earlier, Capstone's arch/SH/SHDisassembler.c sh_disassemble() function computes an idx value from a raw 16-bit instruction without ensuring it is within the active mode-specific decode[] function-pointer table. An application using CS_ARCH_SH with CS_MODE_SH2A or CS_MODE_SH4A and CS_MODE_SHFPU can pass crafted bytecode through cs_disasm_iter() or cs_disasm(), causing the decode[idx] test to read outside the table and terminate the process with a segmentation fault. No code execution or information disclosure was demonstrated. This issue is fixed in version 6.0.0-Alpha10.

Patch / fix

  • capstone-engine capstone 6.0.0-alpha10
  • capstone hummingbird 1 5.0.8-0.3.hum1
  • capstone-java hummingbird 1 5.0.8-0.3.hum1
  • python3-capstone hummingbird 1 5.0.8-0.3.hum1

red hat advisories RHSA-2026:59419

  • rust Azure Linux 3.0 1.96.1-1

azure linux advisories AZL-97413

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-55894 updated cvss 5.5

capstone: Capstone: Denial of Service via crafted SH2A bytecode

  • Red Hat Enterprise Linux 9 capstone, capstone-java, python3-capstone Red Hat Enterprise Linux 10 capstone Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Hardened Images capstone 5.0.8-0.3.hum1, capstone-java 5.0.8-0.3.hum1, python3-capstone 5.0.8-0.3.hum1
    fixed: vendor fix RHSA-2026:59419

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

0.19% chance of exploitation in the next 30 days, higher than 9% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/capstone-engine/capstone/security/advisories/GHSA-gf2c-xwcp-hvf4 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 6.8 CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CNA 4.0 6.8 CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/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

Affected products

  • capstone-engine capstone

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.