8.8

CVE-2026-66032: libssh2 Double Free

CVSS: 8.8v3.1HighAnalyzed
AliasesUBUNTU-CVE-2026-66032DEBIAN-CVE-2026-66032CGA-3xq4-995h-jpcq
Published 24-07-2026Last modified 28-07-2026
Open JSON

Vulnerability summary

CVE-2026-66032 is a high (CVSS 8.8) Double Free vulnerability in libssh2. EPSS estimates a 0.45% chance of exploitation in the next 30 days, higher than 37.6% of scored vulnerabilities.

Overall risk
35/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.8/10
010
High · v3.1 (CVE.org)
EPSS score
0.45%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 16 · Related 13
MGASA-2026-0402OPENSUSE-SU-2026:11454-1OPENSUSE-SU-2026:21549-1RHSA-2026:46927RHSA-2026:61752SUSE-SU-2026:23049-1

Timeline

  1. 24-07-2026
    PublishedVulnerability first disclosed.
  2. 28-07-2026
    Last modifiedVulnerability information updated.

Description

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.

CVSS metrics

9 scores · 6 sources · 2 versions

EPSS trend

Probability

0.45%

Chance of exploitation in the next 30 days

Percentile

38%

Versus all other CVEs

30-day change

0.00 pp

From 0.45% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.45%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Chainguard3 products
  • libssh2All versions (No fix recorded)
  • libssh2-devAll versions (No fix recorded)
  • libssh2-docAll versions (No fix recorded)
Wolfi3 products
  • libssh2All versions (No fix recorded)
  • libssh2-devAll versions (No fix recorded)
  • libssh2-docAll versions (No fix recorded)
Debian1 product
  • libssh2< 1.10.0-3+deb12u1 | < 1.11.1-1+deb13u2 | < 1.11.1-5
Libssh21 product
Ubuntu1 product
  • libssh2< 1.4.3-2ubuntu0.2+esm4 | < 1.5.0-2ubuntu0.1+esm3 | < 1.8.0-1ubuntu0.1+esm1 | < 1.8.0-2.1ubuntu0.1+esm1 | < 1.10.0-3ubuntu0.1 | < 1.11.0-4.1ubuntu0.24.04.4 | < 1.11.1-1ubuntu0.26.04.4

5 vendors · 9 products

References

11 links
Show all 11 references