CVE-2026-35195Network attack vector

Host crash or corruption via unchecked realloc pointer

Published Apr 9, 2026 · Updated Apr 9, 2026

Out-of-bounds write in Bytecode Alliance Wasmtime allows attackers to crash the host or corrupt host data via a crafted guest component. During Component Model string transcoding, the host accepts an unvalidated pointer returned by a guest realloc function and writes up to 4 GiB of transcoded bytes relative to the linear-memory base. The default 4 GiB reservation directs the write into unmapped memory and aborts the process; smaller reservations without guard pages expose host structures or other guests' memories to corruption.

CVSS severity6.1
Medium
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in Bytecode Alliance Wasmtime allows attackers to crash the host or corrupt host data via a crafted guest component. During Component Model string transcoding, the host accepts an unvalidated pointer returned by a guest realloc function and writes up to 4 GiB of transcoded bytes relative to the linear-memory base. The default 4 GiB reservation directs the write into unmapped memory and aborts the process; smaller reservations without guard pages expose host structures or other guests' memories to corruption.

The record

CVE
CVE-2026-35195
Published
Apr 9, 2026
Updated
Apr 9, 2026
Vendor
Bytecode Alliance
Product
Wasmtime
Classifications
CWE-787, T1499.004
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=< 24.0.7
  2. Affected versionversion=>= 25.0.0, < 36.0.7
  3. Affected versionversion=>= 37.0.0, < 42.0.2
  4. Affected versionversion=>= 43.0.0, < 44.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Bytecode Alliance · Wasmtimeversion=< 24.0.7; version=>= 25.0.0, < 36.0.7; version=>= 37.0.0, < 42.0.2; version=>= 43.0.0, < 44.0.1

Published CVSS scores

6.1GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N
5.4NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/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-787Out-of-bounds Write
T1499.004Application or System Exploitation

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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