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Full vulnerability report · 2026
CVE-2026-53783High confidence

rsync < 3.5.0 TOCTOU Race Condition Directory Escape via rrsync

RsyncProject · rsync

8.6HighCVSS 4.0
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
Distribution package intelligence

Ubuntu vendor package status

Canonical’s release and source-package findings are shown separately from local repository availability.

1 package state
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Ubuntu releaseSource packageVendor stateFixed versionEvidence
Ubuntu 24.04 LTSnoble · standard archiversyncUnder evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical record ↗Source updated 11 Sept 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2026-53783 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityrsync: rsync: Directory escape via TOCTOU race condition in rrsync
15 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • rsync as a component of Red Hat Enterprise Linux 10
  • rsync-daemon as a component of Red Hat Enterprise Linux 10
  • rsync-rrsync as a component of Red Hat Enterprise Linux 10
  • rsync.src as a component of Red Hat Enterprise Linux 10
  • rsync as a component of Red Hat Enterprise Linux 6
  • rsync.src as a component of Red Hat Enterprise Linux 6
  • rsync as a component of Red Hat Enterprise Linux 7
  • rsync.src as a component of Red Hat Enterprise Linux 7
  • rsync as a component of Red Hat Enterprise Linux 8
  • rsync-daemon as a component of Red Hat Enterprise Linux 8
  • rsync.src as a component of Red Hat Enterprise Linux 8
  • rsync as a component of Red Hat Enterprise Linux 9
Summary
A time-of-check to time-of-use (TOCTOU) race condition flaw in the rrsync restricted shell wrapper allows authenticated remote attackers to escape directory restrictions. By replacing a validated path component with a symbolic link prior to file transfer execution, an attacker can bypass intended boundary controls and read or write arbitrary files outside the designated directory.
Remediation
Do not use the rrsync SSH forced-command wrapper until patched packages are applied. If restricted rsync over SSH is strictly required, grant access only to SSH identities that are fully trusted with the host account's entire filesystem privileges, as rrsync cannot safely enforce directory boundaries. Note that standard rsync daemon firewall controls (TCP 873) do not mitigate this flaw, as execution occurs entirely over SSH (TCP 22).
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-58090

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

rsync before 3.5.0 contains a time-of-check to time-of-use (TOCTOU) race condition vulnerability in the rrsync restricted shell wrapper that allows authenticated clients to escape enforced directory restrictions by substituting a symlink for a path component after validation but before transfer processing. Attackers can additionally leverage unrestricted flags such as --copy-unsafe-links, -D, and --log-file through rrsync to read or write files outside the permitted directory subtree.

What

rsync before 3.5.0 contains a time-of-check to time-of-use (TOCTOU) race condition vulnerability in the rrsync restricted shell wrapper that allows authenticated clients to escape enforced directory restrictions by substituting a symlink for a path component after validation but before transfer processing. Attackers can additionally leverage unrestricted flags such as --copy-unsafe-links, -D, and --log-file through rrsync to read or write files outside the permitted directory subtree.

Why

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

How

An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

rsync before 3.5.0 contains a time-of-check to time-of-use (TOCTOU) race condition vulnerability in the rrsync restricted shell wrapper that allows authenticated clients to escape enforced directory restrictions by substituting a symlink for a path component after validation but before transfer processing. Attackers can additionally leverage unrestricted flags such as --copy-unsafe-links, -D, and --log-file through rrsync to read or write files outside the permitted directory subtree.

Why

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

How

An attacker operating through a network path may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Improper Link Resolution Before File Access ('Link Following') → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
Low: a basic authenticated account is required
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Not a CVSS 4.0 base metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-59 ↗

CWE-59: Improper Link Resolution Before File Access ('Link Following'). The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Common Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATNoneAttack requirements: No additional deployment or execution condition is required.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.VCHighVulnerable-system confidentiality: A successful attack can cause a major loss.VIHighVulnerable-system integrity: A successful attack can cause a major loss.VANoneVulnerable-system availability: No direct loss is represented by this metric.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkCWE-59
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-2026-2817Rsync: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Rsync ausnutzen, um seine Privilegien zu erhöhen, beliebigen Code auszuführen, Daten offenzulegen oder zu manipulieren, Sicherheitsmaßnahmen zu umgehen oder Denial-of-Service-Zustände herbeizuführen.

Official advisory
CSIRT Italia · Italian · rilevate-vulnerabilita-in-rsync-1Rilevate vulnerabilità in Rsync

Rilevate 19 vulnerabilità, di cui 5 con gravità “critica” e 14 con gravità "alta", in Rsync, software open source per la sincronizzazione e il trasferimento di file tra sistemi.

Official advisory
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
rsync as a component of Red Hat Enterprise Linux 10; rsync-daemon as a component of Red Hat Enterprise Linux 10; rsync-rrsync as a component of Red Hat Enterprise Linux 10; rsync.src as a component of Red Hat Enterprise Linux 10; rsync as a component of Red Hat Enterprise Linux 6; rsync.src as a component of Red Hat Enterprise Linux 6; rsync as a component of Red Hat Enterprise Linux 7; rsync.src as a component of Red Hat Enterprise Linux 7; rsync as a component of Red Hat Enterprise Linux 8; rsync-daemon as a component of Red Hat Enterprise Linux 8; rsync.src as a component of Red Hat Enterprise Linux 8; rsync as a component of Red Hat Enterprise Linux 9; rsync-daemon as a component of Red Hat Enterprise Linux 9; rsync-rrsync as a component of Red Hat Enterprise Linux 9; rsync.src as a component of Red Hat Enterprise Linux 9
Fixed
rsync: 3.5.0
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
Do not use the rrsync SSH forced-command wrapper until patched packages are applied. If restricted rsync over SSH is strictly required, grant access only to SSH identities that are fully trusted with the host account's entire filesystem privileges, as rrsync cannot safely enforce directory boundaries. Note that standard rsync daemon firewall controls (TCP 873) do not mitigate this flaw, as execution occurs entirely over SSH (TCP 22).
04

Evidence and provenance

Published 13 Aug 2026 · Last source change 14 Aug 2026, 16:50 UTC · CWE-59 · Improper Link Resolution Before File Access ('Link Following')

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2026-58090
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD awaiting enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates →

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2026-58090↗Vendor CSAF · Red Hat Product Security↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-53783 · cve.blacktree.nl