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CVE Record

CVE-2026-43618: Rsync < 3.4.3 Integer Overflow Information Disclosure

Rsync version 3.4.2 and prior contain an integer overflow vulnerability in the compressed-token decoder where a 32-bit signed counter is not checked for overflow, allowing a malicious sender to trigger an overflow that causes the receiver process to read and return data from outside the intended buffer bounds. Attackers can exploit this vulnerability to disclose process memory contents including environment variables, passwords, heap and stack data, and library memory pointers, significantly reducing ASLR effectiveness and facilitating further exploitation.

HighCVSS 8.1Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A malicious rsync sender can make an affected receiver expose unrelated process memory and potentially disrupt service. Leaked data may include credentials, environment variables, application memory, and address information useful in later attacks. The supplied record rates this high severity at CVSS 8.1.

Executive priority

Prioritize remediation for externally reachable or cross-trust rsync receivers because successful abuse could expose credentials and weaken exploit defenses. Patch promptly through normal emergency-change procedures; isolated systems accepting only trusted senders may follow after exposure is verified.

Technical view

In rsync 3.4.2 and earlier, an unchecked 32-bit signed counter can overflow during compressed-token decoding. This can cause an out-of-bounds read whose contents are returned to the sender. The stated consequences are high confidentiality and availability impact, without direct integrity impact.

Likely exposure

Exposure exists where rsync 3.4.2 or earlier receives compressed data from a malicious or compromised sender. Network-reachable services and workflows permitting less-trusted peers deserve immediate review. Actual exposure depends on deployed package versions, operating mode, access controls, and whether distribution backports include the fix.

Exploitation context

The CVSS vector indicates network access, low attack complexity, low privileges, and no user interaction. The supplied record does not list this CVE in KEV, and no provided source establishes active exploitation. Treat exploitation status as unconfirmed rather than absent.

Researcher notes

The weakness maps to CWE-190 and CWE-125: signed integer overflow leading to an out-of-bounds read in the compressed-token decoder. The record says memory is returned to the malicious sender and may disclose heap, stack, environment, password, and library-pointer data. Package-version conclusions require vendor backport verification.

Mitigation direction

  • Upgrade upstream rsync to version 3.4.3 or later.
  • Apply the applicable distribution security update when using vendor-packaged rsync.
  • Restrict rsync access to trusted, authenticated senders until remediation is complete.
  • Check vendor guidance before adopting any alternative workaround.

Validation and detection

  • Inventory rsync versions across servers, containers, appliances, and automation environments.
  • Identify receivers accepting connections or data from untrusted or externally reachable senders.
  • Confirm vendor package changelogs explicitly include CVE-2026-43618 remediation.
  • After updating, verify the effective binary and package versions on each system.
  • Review rsync process logs for crashes or unusual transfers; these are indicators, not proof of exploitation.
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

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-125: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-190: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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description · low confidence lookup

Credential and access behavior lookup

The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-43618 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.1 (3.1)
Known Exploited
No
Published

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

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.

3CVSS vectors
5Timeline events
2ADP providers
11Source links

SSVC decision data

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

CVSS vector scores

3 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
8.1CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H2.85.2VulnCheck
8.1CVSS 3.1HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H2.25.9redhat-SADP
6.1CVSS 4.0MediumCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:H/SC:N/SI:N/SA:N——VulnCheck

Vulnerability scoring details

Base CVSS 4.0 score

6.1Medium
CVSS 4.0 vector shape for CVE-2026-43618Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:H/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. ADP timelineredhat-SADP

    Reported to Red Hat.

  3. ADP timelineredhat-SADP

    Made public.

  4. CVE publishedCVE Program

    The CVE record was published.

  5. CVE updatedCVE Program

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

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPrsync: rsync: Remote memory disclosure via integer overflow in compressed-token decoding
other:Red Hat severity ratingcvssV3_1
  • 2026-05-11T13:09:39.838Z: Reported to Red Hat.
  • 2026-05-20T00:00:00.000Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
RsyncProjectrsync0unaffected
Weakness

CWE details

CWE-125CWE-190

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

CWE-125 · source CWE mapping

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.

Open CWE intelligenceSame-CWE CVEs
CWE-190 · source CWE mapping

Integer Overflow or Wraparound

Integer Overflow or Wraparound represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs