dbcve.org
Integer OverflowWeakness · CWE-190

CVE-2026-8295

MEDIUM · 6.9 CVSS v4.0 Published 2026-05-14
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
78/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
An integer overflow vulnerability in the simdjson document-builder API allows incorrect buffer size calculations in "string_builder::escape_and_append()" when processing very large input strings on platforms with limited "size_t" width (e.g., 32-bit builds). The overflow can cause insufficient buffer allocation, leading to out-of-bounds memory reads in SIMD routines and potentially resulting in information disclosure, memory corruption, or malformed JSON output. This vulnerability has been fixed in 4.6.4 release

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Integer overflow in simdjson's string_builder::escape_and_append() function causes incorrect buffer size calculations when processing large input strings on 32-bit platforms. This leads to undersized buffer allocation, resulting in out-of-bounds memory reads during SIMD operations that can cause information disclosure, memory corruption, or malformed JSON output.

MitigationUpgrade to simdjson version 4.6.4 or later. For 32-bit deployments, implement explicit overflow checks in size calculations before buffer allocation and validate input string lengths against platform-specific limits.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify if simdjson is present in the environment
    Search for simdjson library files, headers, or dependencies. Look for files named simdjson.h, simdjson.cpp, libsimdjson.a/so/dylib, or check build dependency files (package.json, CMakeLists.txt, requirements.txt, etc.) for simdjson references.
    Affected if simdjson library or its code is found in the environment
  2. Determine the installed simdjson version
    Check the version string in the library binary, header file (often in SIMDJSON_VERSION or similar macro), or version info in dependency manifests. Compare against the fixed version 4.6.4.
    Affected if The installed version is lower than 4.6.4 or the version cannot be determined (assumed vulnerable)
  3. Identify the target platform architecture
    Check the build target or runtime environment architecture. On Linux, run 'uname -m' or check the compiled binary architecture with 'file <binary>'. Look for 32-bit indicators like 'i386', 'i686', 'x86' (32-bit) in the output.
    Affected if The environment targets or runs on a 32-bit platform (i386, i686, or similar 32-bit architectures)
  4. Determine if string_builder is used for processing input
    Inspect source code or binary for usage of string_builder class and specifically the escape_and_append() method. Search code for 'string_builder', 'escape_and_append', or review API usage in the application.
    Affected if The application uses string_builder to process JSON strings, particularly with user-controlled or large input data

The environment is affected if simdjson version is below 4.6.4, the application runs on or targets a 32-bit platform, and uses string_builder to process potentially large input strings that could trigger the integer overflow in escape_and_append().

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to simdjson version 4.6.4 or later. For 32-bit deployments, implement explicit overflow checks in size calculations before buffer allocation and validate input string lengths against platform-specific limits.

Recommended fix High confidence

4.6.4

  1. Identify the current version of simdjson in use by checking project dependencies or build configuration
  2. Upgrade simdjson to version 4.6.4 or later using the appropriate package manager or build system (e.g., CMake, vcpkg, conan, or system package manager)
  3. Rebuild the project to incorporate the fixed library version
  4. Verify the build completes successfully and test the application to ensure functionality is intact
  5. For 32-bit builds specifically, test with large input strings to confirm the overflow condition is resolved
Caveat Review the 4.6.4 release notes for any API changes or deprecations that may affect existing code using the document-builder API

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing4.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,900
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-8295 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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