CVE Intelligence
Critical

CVE-2026-115893 — Wasmtime: Cranelift backend on aarch64 can jump to incorrect target on large Wasm `br_table` instruction

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.

Published Oct 23, 2026 · Updated Oct 29, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: GitHub_M

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 1% (30-day exploitation probability)+9
  • Technical severity (critical)+10

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.99%
ahead of 62% of scored CVEs · Oct 29, 2026
Affects
Bytecodealliance
Wasmtime
CVSS base
9.9
Critical · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Total
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

  • Rust Wasmtime: fixed in version 36.0.19 — github.com (GitHub Security Advisories)
  • Rust Wasmtime: fixed in version 48.0.7 — github.com (GitHub Security Advisories)
  • Rust Wasmtime: fixed in version 49.0.4 — github.com (GitHub Security Advisories)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Bytecodealliance Wasmtime, Rust Wasmtime).
  2. Apply the fixed version or the patch documented under Remediation.
  3. Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Bytecodealliance Wasmtime version < 36.0.19version >= 37.0.0, < 48.0.7version >= 49.0.0, < 49.0.4 Vulnerable CVE Program (cve.org) e CISA ADP
Rust Wasmtime < 36.0.19≥ 37.0.0 and < 48.0.7≥ 49.0.0 and < 49.0.4 Vulnerable GitHub Security Advisories

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
9.9 CVSS 3.1 Critical 3.1 6.0 security-advisories@github.com via NIST National Vulnerability Database
9.9 CVSS 3.1 Critical — — GitHub, Inc. via GitHub Security Advisories
9.9 CVSS 3.1 Critical — — GitHub_M via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H (score shown at the top: security-advisories@github.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-691

Other CVEs with this weakness →

EPSS over time FIRST

Oct 24, 2026 → Oct 29, 2026 · 6 reading(s) · max 0.99%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

  • 2026
  • Fix documented
    Oct 29, 2026 · GitHub Security Advisories
  • Affected products added · rust/wasmtime
    Oct 29, 2026 · GitHub Security Advisories
  • SSVC assessment updated
    Oct 29, 2026 · CVE Program (cve.org) e CISA ADP
  • Affected products added · bytecodealliance/wasmtime
    Oct 23, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 23, 2026
  • CVSS changed · 9.9
    Oct 23, 2026 · NIST National Vulnerability Database
  • Source status changed · → Deferred
    Oct 23, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 23, 2026 · NIST National Vulnerability Database
  • CVE published
    Oct 23, 2026 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

  • 1× References added · Oct 29, 2026 – Oct 29, 2026
  • 1× Official description updated · Oct 23, 2026 – Oct 23, 2026

References

15 on the record

Elsewhere on this site

Bytecodealliance
every CVE for this vendor
CWE-691
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-119140 Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 Host Panic via thread.yield 1d
  • CVE-2026-119137 Wasmtime 42.0.0 before 48.0.6 and 49.0.0 before 49.0.3 Stack Overflow via Type Registry 1d
  • CVE-2026-119141 Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 Host Panic via realloc 1d
  • CVE-2026-119142 Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 Host Panic via call_async Drop 1d
  • CVE-2026-119138 Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 Panic After Trap 1d
  • CVE-2026-119143 Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 Panic via Zero-Length Stream Writes 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-115893 is "Wasmtime: Cranelift backend on aarch64 can jump to incorrect target on large Wasm `br_table` instruction", rated Critical. It affects Wasmtime (Bytecodealliance); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.9 describes technical severity. EPSS 0.99% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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