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CVE Record

CVE-2026-45232: Rsync < 3.4.3 Off-by-One Stack Write via HTTP Proxy

Rsync versions before 3.4.3 contain an off-by-one out-of-bounds stack write vulnerability in the establish_proxy_connection() function in socket.c that allows network attackers to corrupt stack memory by sending a malformed HTTP proxy response. Attackers can exploit this by positioning themselves between the client and proxy or controlling the proxy server to send a response line of 1023 or more bytes without a newline terminator, causing a null byte to be written to an out-of-bounds stack address when the RSYNC_PROXY environment variable is set.

LowCVSS 3.1Not KEV-listedUpdated
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Glexia's TakeAutomated analysislow

Security readout for executives and security teams

Plain-English summary

This is a narrow rsync client-side issue. If an organization runs vulnerable rsync through an HTTP proxy using RSYNC_PROXY, a malicious or intercepted proxy response can corrupt stack memory and likely disrupt the rsync process. The published CVSS impact is low and does not claim data theft or privilege gain.

Executive priority

Treat as routine patching unless rsync-over-proxy is operationally important. Prioritize internet-adjacent automation, managed file-transfer systems, and environments where proxy trust cannot be assured.

Technical view

Rsync before 3.4.3 has an off-by-one out-of-bounds stack write in establish_proxy_connection() in socket.c. A malformed HTTP proxy response line of 1023 or more bytes without a newline can cause an out-of-bounds null-byte write when RSYNC_PROXY is set.

Likely exposure

Exposure is limited to rsync clients configured to use an HTTP proxy through the RSYNC_PROXY environment variable. Systems not using that proxy path are not indicated as exposed by the provided sources.

Exploitation context

The bundle does not identify active exploitation, and KEV is false. Exploitation requires user interaction, high attack complexity, and either proxy control or a network position between the client and proxy.

Researcher notes

The key exposure condition is RSYNC_PROXY. The affected metadata in the bundle is sparse, so rely on the vendor advisory, 3.4.3 release notes, and distribution advisories for exact package status.

Mitigation direction

  • Upgrade rsync to version 3.4.3 or later where available.
  • Check vendor, OS, and package-maintainer guidance for backported fixes.
  • Remove or avoid RSYNC_PROXY where proxying rsync is not required.
  • Use only trusted HTTP proxies and protected network paths for rsync traffic.

Validation and detection

  • Inventory rsync versions on systems and build images.
  • Search deployment scripts, cron jobs, and service units for RSYNC_PROXY usage.
  • Confirm patched package versions or vendor backport status after updates.
  • Identify rsync workflows that traverse HTTP proxies.
Prepared
Confidence
high
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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 · low confidence lookup

CWE-193: Exact CWE lookup

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cve · low confidence lookup

CVE-2026-45232 mapping review

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Vulnerability profileCVE Program record
Severity
Low
CVSS
3.1 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L

Official CVE source material

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.

2CVSS vectors
3Timeline events
1ADP providers
4Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

2 official scores

We 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.

ScoreVersionSeverityVectorExploitImpactSource
3.1CVSS 3.1LowCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L1.61.4VulnCheck
2.1CVSS 4.0LowCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N——VulnCheck

Vulnerability scoring details

Base CVSS 4.0 score

2.1Low
CVSS 4.0 vector shape for CVE-2026-45232Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
RsyncProjectrsync0unaffected
Weakness

CWE details

CWE-193

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.