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CVE-2026-45232· NVD / CVE Program· CNA VulnCheck

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 2.1 · v4.0—No exploit Fix available
Published
May 19, 2026
Updated
Jul 24, 2026
EPSS
0.3% · 26th percentile
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Report tools

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Action score

8

Monitor

Low priority for now.

CVSS
8 / 40 · 2.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · VulnCheck
2.1
NVD has not scored this yet; the score shown is the CNA’s.

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

VendorProduct
sambarsync

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • samba rsyncbefore 3.4.3

Versions reported by the vendor

Affected version ranges reported by the assigning authority (VulnCheck). Independent of NVD's CPE analysis and usually ahead of it.

  • RsyncProject rsync

    • before 3.4.3affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Alpine:v3.20rsyncbefore 3.4.3-r03.4.3-r0
Debian:12rsyncbefore 3.2.7-1+deb12u63.2.7-1+deb12u6
Debian:13rsyncbefore 3.4.1+ds1-5+deb13u43.4.1+ds1-5+deb13u4
Debian:14rsyncbefore 3.4.3+ds1-13.4.3+ds1-1
openSUSE:Tumbleweedrsyncbefore 3.4.3-1.13.4.3-1.1
SUSE:Linux Enterprise Server 16.0rsyncbefore 3.4.1-160000.4.13.4.1-160000.4.1

Same product

samba: all records

Other highest-scoring records for the same primary product.

  • CVE-2024-12084Rsync: heap buffer overflow in rsync due to improper checksum length handling
    61This week
  • CVE-2017-16548The receive_xattr function in xattrs.c in rsync 3.1.2 and 3.1.3-development does not check for a trailing '\0' character in an xattr name, w
    41Plan
  • CVE-2017-17434The daemon in rsync 3.1.2, and 3.1.3-development before 2017-12-03, does not check for fnamecmp filenames in the daemon_filter_list data str
    40Plan
  • CVE-2017-15994rsync 3.1.3-development before 2017-10-24 mishandles archaic checksums, which makes it easier for remote attackers to bypass intended access
    39Monitor
  • CVE-2026-53791rsync < 3.5.0 Daemon IP Spoofing via PROXY Protocol Header
    36Monitor
  • CVE-2026-70461rsync 3.2.5 < 3.5.0 Heap Out-of-Bounds Write via files-from Entry
    35Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
RsyncProject rsync3.4.3Vendor (CNA)
alpine:rsync3.4.3-r0 · Alpine:v3.20Package registry (OSV)
debian:rsync3.2.7-1+deb12u6 · Debian:12Package registry (OSV)
opensuse:rsync3.4.3-1.1 · openSUSE:TumbleweedPackage registry (OSV)
suse:rsync3.4.1-160000.4.1 · SUSE:Linux Enterprise Server 16.0Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
A
Scope
X

Weakness class (CWE)

CWE-193 · Off-by-one Error

CVSS 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records