CVE-2026-43618
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedRsync 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceRsync versions 3.4.2 and prior contain an integer overflow in the compressed-token decoder where a 32-bit signed counter is not validated, allowing a malicious sender to trigger an overflow that causes the receiver to read beyond buffer boundaries. This enables memory disclosure including environment variables, passwords, heap/stack data, and library pointers, weakening ASLR and enabling further exploitation.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data<= 3.4.2CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Determine installed rsync versionRun 'rsync --version' and look for the version number in the output (e.g., 'version 3.4.2' or earlier)Affected if The version shown is 3.4.2 or any earlier version (e.g., 3.4.1, 3.4.0, 3.3.x, etc.)
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Verify rsync daemon mode configurationCheck /etc/rsyncd.conf or look for rsyncd daemon processes with 'ps aux | grep rsyncd' or check for rsync daemon configuration files in /etc/Affected if Rsync is configured as a daemon (server) accessible to network clients, or is being used in a setup where untrusted remote systems can act as the rsync sender
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Identify if compression is enabledReview rsync command invocations or daemon configurations for the -z, --compress, or --compress-level options, or check for 'compress' settings in rsyncd.conf modulesAffected if Compression is enabled in any rsync usage (client or server) because the vulnerability exists in the compressed-token decoder path
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Assess network exposureReview firewall rules, ACLs, or network segmentation around systems running rsync; check if rsync ports (873/tcp) are exposed to untrusted networksAffected if Rsync can be reached by untrusted or attacker-controlled network peers who could act as a malicious sender
A system is affected if it runs rsync version 3.4.2 or prior with compression enabled and accepts connections from untrusted remote sources.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUpgrade rsync to a version beyond 3.4.2 that addresses the integer overflow vulnerability; if immediate upgrading is not feasible, restrict or authenticate connections from remote rsync servers to prevent untrusted senders from triggering the overflow.
- Consultation2.0 h
- Implementation2.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-43618 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-43618 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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