CVE-2026-34988Network attack vector

Cross-instance data exposure via skipped permission reset

Published Apr 9, 2026 · Updated Apr 9, 2026

Memory exposure in Wasmtime 28.0.0 through 36.0.6, 37.0.0 through 42.0.1, and 43.0.0 allows remote authenticated users to read prior data. The pooling allocator uses a runtime predicate that can skip resetting linear-memory VM permissions even though compiled code assumes guard enforcement. The flaw requires pooling allocation, a zero memory guard, a sub-4-GiB reservation, and max_memory_size equal to that reservation; defaults are unaffected.

CVSS severity2.3
Low
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory exposure in Wasmtime 28.0.0 through 36.0.6, 37.0.0 through 42.0.1, and 43.0.0 allows remote authenticated users to read prior data. The pooling allocator uses a runtime predicate that can skip resetting linear-memory VM permissions even though compiled code assumes guard enforcement. The flaw requires pooling allocation, a zero memory guard, a sub-4-GiB reservation, and max_memory_size equal to that reservation; defaults are unaffected.

The record

CVE
CVE-2026-34988
Published
Apr 9, 2026
Updated
Apr 9, 2026
Vendor
Bytecode Alliance
Product
Wasmtime
Classifications
CWE-119, T1005
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 28.0.0, < 36.0.7
  2. Affected versionversion=>= 37.0.0, < 42.0.2
  3. Affected versionversion=>= 43.0.0, < 44.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Bytecode Alliance · Wasmtimeversion=>= 28.0.0, < 36.0.7; version=>= 37.0.0, < 42.0.2; version=>= 43.0.0, < 44.0.1

Published CVSS scores

2.3GitHub, Inc.CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N
6.3NIST NVDCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
T1005Data from Local System

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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