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Libssh2 EUVDEUVD-2026-48719

| CVE-2026-66032 HIGH
Double Free (CWE-415)
2026-07-24 VulnCheck GHSA-83r8-6c29-8gwr
Information Disclosure Libssh2
8.7
CVSS 4.0 · Vendor: VulnCheck
View

Vulnerability Assessment

Weakness
CWE
CWE-415
ASVS 5.0
V15 - Secure Coding and Architecture Double free prevention
This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Jul 27, 2026

Double-free heap corruption in libssh2's SFTP client allows a malicious SSH server to corrupt the memory of any authenticated client that opens an SFTP session. This vulnerability, present in libssh2 through 1.11.1, can be triggered via a crafted server response during the sftp_open() operation, leading to tcache poisoning and potential arbitrary code execution on the client. No active exploitation has been confirmed, and no public PoC is known at this time, though the EPSS score is low (0.29%).

Affected VersionsENISA

libssh2 patch: 5e4776146552d898b9c0e1b313cd093fa8dc92d0
libssh2 0 ≤1.11.1

Affected Packages

euvd libssh2 no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

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Severity by source

Vendor (VulnCheck) PRIMARY 8.7 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
SUSE 8.8 HIGH
AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Red Hat 6.5 MEDIUM

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
Passive
Vulnerable system: Confidentiality
High
Vulnerable system: Integrity
High
Vulnerable system: Availability
High
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

DescriptionCVE.org

libssh2 through 1.11.1, fixed in commit 5e47761, contains a double-free vulnerability in the sftp_open() function in src/sftp.c that allows a malicious SSH server to corrupt the heap of any authenticated client opening an SFTP session. When a server responds to SSH_FXP_OPEN with SSH_FXP_STATUS containing FX_OK, the response data buffer is freed, and if a subsequent sftp_packet_require() call returns a specific error such as LIBSSH2_ERROR_CHANNEL_PACKET_EXCEEDED, the same pointer is freed a second time, enabling tcache dup conditions on glibc systems that allow overlapping allocations and function pointer overwrites.

Threat Intelligence Overview

EPSS Score
0.3%
Top 79% exploitable
Social Media
1
Sightings
Data Quality
9 sources
Confidence: High
EUVD NVD CVE.org EPSS Vulnrichment MSRC Vendor CIRCL GitHub VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.3%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Total

Priority Score

44
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +44
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

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Same weakness CWE-415 – Double Free

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CVE-2016-5768 CRITICAL POC
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CVE-2016-5772 CRITICAL POC
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Same technique Information Disclosure

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CVE-2019-2725 CRITICAL POC
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CVE-2021-34523 CRITICAL POC
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CVE-2013-2251 CRITICAL POC
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CVE-2017-5638 CRITICAL POC
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CVE-2025-24813 CRITICAL POC
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CVE-2025-68613 HIGH POC
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CVE-2015-1701 HIGH POC
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CVE-2017-0147 HIGH POC
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Vendor StatusVendor

SUSE

Severity: Important
Product Status
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS Affected
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS Affected
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS Affected
SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS Affected
SUSE Linux Enterprise Micro 5.3 Affected

References

Advisories & patches
PATCH https://github.com/libssh2/libssh2/commit/5e4776146552d898b9c0e1b313cd093fa8dc92d0 ADVISORY https://access.redhat.com/errata/RHSA-2026:46927 ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-66032 ADVISORY https://ubuntu.com/security/notices/USN-8722-1 ADVISORY https://vuldb.com/vuln/382985 REF https://github.com/libssh2/libssh2/pull/2180 REF https://www.vulncheck.com/advisories/libssh2-double-free-heap-corruption-via-sftp-open

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