CVE-2026-66032
HIGHDescription
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.
How to fix
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This Red Hat / RHEL release reached end-of-life on 2024-06-30. Extended security maintenance is available until 2029-05-31.
This vulnerability affects an unusually large number of packages. The highest-confidence fixes are shown above; the full list is longer. Check the referenced advisories for complete coverage.
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Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Exploit Intelligence
Low risk: more likely to be exploited than 38% of all known CVEs.
References
Related Vulnerabilities
Other CWE-415 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2023-25136 | Medium | 6.5 | 90% | - | Fix |
| CVE-2003-0545 | Critical | 9.8 | 87% | - | Fix |
| CVE-2018-0101 | Critical | 10.0 | 87% | - | Fix |
| CVE-2026-33824 | Critical | 9.8 | 73% | KEV | Fix |
| CVE-2019-3829 | Medium | 5.3 | 59% | - | Fix |
| CVE-2021-3407 | Medium | 5.5 | 50% | - | Fix |
Common questions
How do I fix CVE-2026-66032?
Published advisories record a fix for 11 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2026-66032 being actively exploited?
Not that we know of. CVE-2026-66032 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.45% is the estimated probability that it will be exploited in the next 30 days. That is higher than 38% of all scored CVEs.
How severe is CVE-2026-66032?
CVE-2026-66032 has a CVSS v3 base score of 8.8, rated important. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-66032 affect?
Published advisories record a fix for libssh2 (Debian), libssh2 (Red Hat / RHEL), libssh2 (Rocky), libssh2-debuginfo (Red Hat / RHEL), and 7 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-07.