CriticalCVE-2026-115893

    Bytecode Alliance wasmtime: Insufficient Control Flow Management (CVE-2026-115893)

    Published Last modified Sources: pwn.watch, Msrc Update Guide, CVE.org, OSV, Hersteller

    What is affected, what to do

    Wasmtime is a runtime for WebAssembly. Prior to 36.0.19, 48.0.7, and 49.0.4, the Cranelift compiler backend on aarch64 can compile a Wasm br_table instruction with more than approximately 256,000 targets so that it has an incorrect conditional branch target.

    Update Bytecode Alliance wasmtime to version 36.0.19.

    Affected
    • Bytecode Alliance wasmtime gte 37.0.0, < 48.0.7..*
    • Bytecode Alliance wasmtime lt *..36.0.19
    Fixed in
    • Bytecode Alliance wasmtime 36.0.19

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    9.9

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: Vendor (CNA), CVSS v3

    9.9

    CVSS v3

    Severity Critical on the scale from 0 to 10.

    Source: pwn.watch, Msrc Update Guide, CVE.org, OSV, Hersteller

    1.0 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 62.4

    Show all metrics
    Severity
    Critical
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    110.68 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    no public PoC known
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    9.9 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    9.9
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    1.0 %
    Low — model estimates < 1% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    62.4
    High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    —
    Published
    CISA assessment (SSVC)
    Exploitation: none known · not automatable · Technical impact: total
    Source: CISA Vulnrichment, as of 29 October 2026
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-691

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    Wasmtime is a runtime for WebAssembly. Prior to 36.0.19, 48.0.7, and 49.0.4, the Cranelift compiler backend on aarch64 can compile a Wasm br_table instruction with more than approximately 256,000 targets so that it has an incorrect conditional branch target. The branch can then jump to arbitrary other code at a user-controlled offset, allowing a user-controlled Wasm module to escape the sandbox on aarch64 engines using the default Cranelift backend. This issue is fixed in versions 36.0.19, 48.0.7, and 49.0.4.

    Source: pwn.watch, Microsoft Security Update Guide, cvelistv5, NVD (NIST), OSV (Open Source Vulnerabilities), GitHub Security Advisories

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    bytecodealliancewasmtime
    • ≥ 37.0.0, < 48.0.7
    • < 36.0.19
    • —
    • 36.0.19
    crates.iowasmtime
    • 37.0.0
    • 49.0.0
    • 0.0.0-0
    • —
    • 48.0.7
    • 49.0.4
    • 36.0.19
    • 36.0.19
    rustwasmtime
    • >= 37.0.0, < 48.0.7
    • < 36.0.19
    • >= 49.0.0, < 49.0.4
    • 48.0.7
    • 36.0.19
    • 49.0.4

    Vendors and products

    Weakness classes (CWE)

    • CWE-691Insufficient Control Flow Management

      Pillar

      The code does not sufficiently manage its control flow during execution, creating conditions in which the control flow can be modified in unexpected ways.

      Entry at MITRE CWE-691

    References & sources

    • github.combytecodealliance/wasmtime/security/advisories/GHSA-mghf-wjfp-p5…x_refsource_CONFIRM, pwn-watch, web
    • github.combytecodealliance/wasmtime/pull/14818x_refsource_MISC, web
    • github.combytecodealliance/wasmtime/pull/14819x_refsource_MISC, web
    • github.combytecodealliance/wasmtime/pull/14820x_refsource_MISC, web
    • github.combytecodealliance/wasmtime/pull/14826x_refsource_MISC, web
    • github.combytecodealliance/wasmtime/commit/222ff3a65dab9aa7011f8c24693775…x_refsource_MISC, web
    • github.combytecodealliance/wasmtime/commit/994549891c8a706cb4f2809f9d17b9…x_refsource_MISC, web
    • github.combytecodealliance/wasmtime/commit/e61df1b454be9313d61a5f8de07722…x_refsource_MISC, web
    • github.combytecodealliance/wasmtime/commit/f517bd6e890c7c1291ab9fe05d8cc0…x_refsource_MISC, web
    • github.combytecodealliance/wasmtime/releases/tag/v36.0.19x_refsource_MISC, web
    • github.combytecodealliance/wasmtime/releases/tag/v48.0.7x_refsource_MISC, web
    • github.combytecodealliance/wasmtime/releases/tag/v49.0.4x_refsource_MISC, web
    • crates.iocrates/wasmtimepackage
    • rustsec.orgadvisories/RUSTSEC-2026-0379.htmladvisory, web
    • pwn.watchpwn.watch: Wasmtime: two critical Cranelift miscompilation bugs let a malicious WebAssembly module escape the sandbox (CVE-2026-115889, CVE-2026-115893)pwn-watch
    • github.comGHSA-897f-g5gm-fmxm: Bit-packing in Cranelift compiler causes silent overflow and miscompilationpwn-watch
    • thehackernews.comTwo Critical Wasmtime Flaws Could Let Malicious WebAssembly Modules Escape Sandboxespwn-watch
    • NVD (NIST)vuln/detail/CVE-2026-115893advisory
    • github.combytecodealliance/wasmtimepackage

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    1. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: none known, automatable: no

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      SSVC assessmentadded
      —
      {"id":"CVE-2026-115893","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-10-29T18:19:46.559873Z"}

      Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

    2. ReceivedGitHub

      CVSS V3.1: AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

      Weakness type: CWE-691

      Description added or changed

      Show 16 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      Wasmtime is a runtime for WebAssembly. Prior to 36.0.19, 48.0.7, and 49.0.4, the Cranelift compiler backend on aarch64 can compile a Wasm br_table instruction with more than approximately 256,000 targets so that it has an incorrect conditional branch target. The branch can then jump to arbitrary other code at a user-controlled offset, allowing a user-controlled Wasm module to escape the sandbox on aarch64 engines using the default Cranelift backend. This issue is fixed in versions 36.0.19, 48.0.7, and 49.0.4.
      CVSSadded
      —
      AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
      Weakness type (CWE)added
      —
      CWE-691
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/115xxx/CVE-2026-115893.json">CVE-2026-115893</a>
      Referenceadded
      —
      https://github.com/bytecodealliance/wasmtime/commit/222ff3a65dab9aa7011f8c246937751a0bac5abd
      Referenceadded
      —
      https://github.com/bytecodealliance/wasmtime/commit/994549891c8a706cb4f2809f9d17b9f67b31e618
      Referenceadded
      —
      https://github.com/bytecodealliance/wasmtime/commit/e61df1b454be9313d61a5f8de07722a421139bbe
      Referenceadded
      —
      https://github.com/bytecodealliance/wasmtime/commit/f517bd6e890c7c1291ab9fe05d8cc0c9f11e56aa
      Referenceadded
      —
      https://github.com/bytecodealliance/wasmtime/pull/14818
      Referenceadded
      —
      https://github.com/bytecodealliance/wasmtime/pull/14819
      Referenceadded
      —
      https://github.com/bytecodealliance/wasmtime/pull/14820
      Referenceadded
      —
      https://github.com/bytecodealliance/wasmtime/pull/14826
      Referenceadded
      —
      https://github.com/bytecodealliance/wasmtime/releases/tag/v36.0.19
      Referenceadded
      —
      https://github.com/bytecodealliance/wasmtime/releases/tag/v48.0.7
      Referenceadded
      —
      https://github.com/bytecodealliance/wasmtime/releases/tag/v49.0.4
      Referenceadded
      —
      https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-mghf-wjfp-p5xm

      Source identifier: security-advisories@github.com

    Embed badge

    Show the severity and KEV status of this vulnerability on your site – with a link back here. The image is updated hourly.

    Badge preview for CVE-2026-115893
    <a href="https://intel.neosec.eu/en/cve/CVE-2026-115893"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-115893.svg?lang=en" alt="CVE-2026-115893 – NEOSEC Intel" height="20"></a>