CVE Intelligence
Medium

CVE-2026-115383 — Wasmtime 47.0.0 before 48.0.4 and 49.0.0 before 49.0.2 GC Heap Corruption via Tag Imports

Wasmtime 47.0.0 before 48.0.4 and 49.0.0 before 49.0.2 contains an improper validation vulnerability that accepts components whose core modules import WebAssembly tags with a subtype of the original type. Malicious guests can mis-type exception object payloads to corrupt the GC heap, causing Wasmtime to panic when the exceptions proposal is enabled.

Published Oct 22, 2026 · Updated Oct 22, 2026 · Sources: CVE Program (cve.org) e CISA ADP, NIST National Vulnerability Database · CNA: VulnCheck

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 0.2% (30-day exploitation probability)+1
  • Technical severity (medium)+3

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
0.18%
ahead of 8% of scored CVEs · Oct 30, 2026
Affects
Bytecodealliance
Wasmtime
CVSS base
4.8
Medium · 2 source(s)

Remediation

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

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

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).
  2. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  3. Exploitation requires user interaction: tighten email/web filtering and warn affected users.
  4. Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Bytecodealliance Wasmtime ≥ 47.0.0 and < 48.0.4≥ 49.0.0 and < 49.0.2 Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

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

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
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
5.9 CVSS 4.0 Medium — — disclosure@vulncheck.com via NIST National Vulnerability Database
5.9 CVSS 4.0 Medium — — VulnCheck via CVE Program (cve.org) e CISA ADP
4.8 CVSS 3.1 Medium 1.2 3.6 disclosure@vulncheck.com via NIST National Vulnerability Database
4.8 CVSS 3.1 Medium — — VulnCheck via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:H (score shown at the top: disclosure@vulncheck.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-1287

Other CVEs with this weakness →

EPSS over time FIRST

Oct 23, 2026 → Oct 30, 2026 · 8 reading(s) · max 0.18%

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
  • Source status changed · Published → Deferred
    Oct 22, 2026 · NIST National Vulnerability Database
  • Record published
    Oct 22, 2026
  • Affected products added · bytecodealliance/wasmtime
    Oct 22, 2026 · CVE Program (cve.org) e CISA ADP
  • CVSS changed · 4.8
    Oct 22, 2026 · CVE Program (cve.org) e CISA ADP
  • Source status changed · → Published
    Oct 22, 2026 · CVE Program (cve.org) e CISA ADP
  • Record created in this database
    Oct 22, 2026 · Alertas do Telegram
  • CVE published
    Oct 22, 2026 · VulnCheck

Source activity

Repeated readings are counted rather than listed.

  • 1× References added · Oct 22, 2026 – Oct 22, 2026
  • 1× Official description updated · Oct 22, 2026 – Oct 22, 2026

References

2 on the record

Elsewhere on this site

Bytecodealliance
every CVE for this vendor
CWE-1287
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 2d
  • CVE-2026-119137 Wasmtime 42.0.0 before 48.0.6 and 49.0.0 before 49.0.3 Stack Overflow via Type Registry 2d
  • CVE-2026-119141 Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 Host Panic via realloc 2d
  • 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 2d
  • CVE-2026-119138 Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 Panic After Trap 2d
  • 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 2d

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 fixed version, patch or mitigation documented.
  • No CISA SSVC assessment.
  • 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-2026-115383 is "Wasmtime 47.0.0 before 48.0.4 and 49.0.0 before 49.0.2 GC Heap Corruption via Tag Imports", rated Medium. It affects Wasmtime (Bytecodealliance); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 4.8 describes technical severity. EPSS 0.18% 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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