Security readout for executives and security teams
Plain-English summary
Rsync clients running version 3.4.2 or earlier can be crashed by a malicious rsync server. The business impact is service disruption, not data theft or remote code execution based on the provided sources. Risk is highest where automated jobs pull data from untrusted or externally controlled rsync servers.
Executive priority
Treat this as a moderate availability risk. Patch during the next normal maintenance cycle, faster where rsync supports backups, software distribution, or operational recovery from untrusted sources.
Technical view
The issue is a receiver-side out-of-bounds array read in recv_files() in receiver.c. A crafted server response can cause the client to read before an allocated pointer array and dereference an invalid pointer, producing a deterministic SIGSEGV. The CVSS 4.0 score is 6.9 with high victim availability impact and user interaction required.
Likely exposure
Exposure is likely limited to environments where rsync clients connect to malicious, compromised, or untrusted rsync servers. Internal backup, mirror, deployment, and synchronization jobs should be reviewed, especially if they pull from third-party endpoints.
Exploitation context
The source bundle does not show KEV listing or active exploitation evidence. Exploitation requires a client to interact with a malicious rsync server. The described outcome is a client crash and availability loss.
Researcher notes
The evidence supports denial of service against the rsync client only. The provided materials do not support confidentiality impact, integrity impact, code execution, or active exploitation claims. Affected scope should be validated against local distribution packaging and backport notes.
Mitigation direction
- Upgrade rsync to version 3.4.3 or a vendor-backported fixed package.
- Restrict automated rsync clients to trusted servers only.
- Review jobs that pull from third-party or internet-accessible rsync endpoints.
- Monitor vendor and OS distribution advisories for package-specific guidance.
- Prioritize systems where rsync failures affect backups, deployments, or recovery workflows.
Validation and detection
- Inventory rsync versions across servers, workstations, containers, and build images.
- Identify scheduled jobs where rsync operates as a client.
- Confirm package metadata maps to rsync 3.4.3 or a documented backport.
- Review recent rsync client crashes or SIGSEGV events for correlation.
- Check whether critical workflows depend on external rsync servers.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
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CWE-125: Exact CWE lookup
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Open ATT&CK lookupCVE-2026-43620 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.9 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N——VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H2.83.6VulnCheckVulnerability scoring details
Base CVSS 4.0 score
6.9MediumVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Base CVSS 3.1 score
6.5MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/RsyncProject/rsync/security/advisories/GHSA-28pw-r563-rxvmCVE reference, VulnCheck · vendor-advisory
- https://github.com/RsyncProject/rsync/releases/tag/v3.4.3CVE reference, VulnCheck · release-notes
- https://www.vulncheck.com/advisories/rsync-out-of-bounds-array-read-via-recv-filesCVE reference, VulnCheck · third-party-advisory
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Out-of-bounds Read
Out-of-bounds Read represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.