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medium 6.5

CVE-2026-58051 json

libssh2 - Free of Uninitialized Pointer in publickey List Cleanup

published 4mo ago modified yesterday also EUVD-2026-39971 , GHSA-c5f3-hwj2-xp5p , JLSEC-2026-663

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 21%
public exploits
0
none known

Summary

libssh2 through 1.11.1 grows its publickey list with SSH2_REALLOC but does not zero-initialize new entries before parsing populates them, so a parse failure reaching the cleanup path leaves libssh2_publickey_list_free operating on an uninitialized entry. A malicious SSH server offering the publickey subsystem can use a malformed response to make cleanup free an uninitialized, attacker-influenceable attrs pointer in a connecting libssh2 client.

Patch / fix

  • julia LibSSH2_jll 1.11.103+0
  • libssh2 Debian 12 1.10.0-3+deb12u1
  • libssh2 Debian 13 1.11.1-1+deb13u2
  • libssh2 Debian 14 1.11.1-6

debian advisories DEBIAN-CVE-2026-58051

  • libssh2 Ubuntu 22.04 LTS 1.10.0-3ubuntu0.1
  • libssh2 Ubuntu 24.04 LTS 1.11.0-4.1ubuntu0.24.04.3
  • libssh2 Ubuntu 26.04 LTS 1.11.1-1ubuntu0.26.04.3
  • libssh2 Ubuntu Pro 14.04 LTS 1.4.3-2ubuntu0.2+esm4
  • libssh2 Ubuntu Pro 16.04 LTS 1.5.0-2ubuntu0.1+esm3
  • libssh2 Ubuntu Pro 18.04 LTS 1.8.0-1ubuntu0.1+esm1
  • libssh2 Ubuntu Pro 20.04 LTS 1.8.0-2.1ubuntu0.1+esm1

ubuntu advisories UBUNTU-CVE-2026-58051

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • libssh2 hummingbird 1 1.11.1-10.2.hum1
  • libssh2 hummingbird 1 1.11.1-10.1.hum1

red hat advisories RHSA-2026:46927RHSA-2026:46535

  • libssh2_org SLES 15 SP4-LTSS, SLE High Performance Computing 15 SP4-LTSS, SLE High Performance Computing 15 SP4-ESPOS 1.11.0-150000.4.35.1
  • libssh2_org Linux Micro 6.0 1.11.0-4.1
  • libssh2_org Linux Micro 6.1 1.11.0-slfo.1.1_2.1
  • libssh2_org SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 1.11.1-160000.5.1
  • libssh2_org SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Basesystem 15 SP7 1.11.0-150600.20.6.1
  • libssh2_org SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +8 more 1.11.0-150200.9.8.1
  • libssh2_org SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 1.11.0-29.18.1

suse advisories SUSE-SU-2026:4095-1SUSE-SU-2026:23245-1SUSE-SU-2026:23187-1SUSE-SU-2026:23049-1SUSE-SU-2026:23214-1SUSE-SU-2026:23225-1

  • libssh2_org openSUSE Leap 16.0 1.11.1-160000.5.1
  • libssh2_org openSUSE Tumbleweed 1.11.1-4.1

opensuse advisories openSUSE-SU-2026:21549-1openSUSE-SU-2026:11454-1

  • libssh2 Alpine 3.22, Alpine 3.21 1.11.1-r3
  • libssh2 Alpine 3.24, Alpine 3.23 1.11.1-r4

alpine advisories ALPINE-CVE-2026-58051

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • libssh2 Azure Linux 3.0 1.11.1-6
  • rust Azure Linux 3.0 1.75.0-30
  • rust Azure Linux 3.0 1.96.0-1

azure linux advisories AZL-91385AZL-97395AZL-97437

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Is CVE-2026-58051 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-58051 updated cvss 6.5

libssh2: libssh2: Denial of service or information disclosure via malformed SSH publickey response

  • Red Hat Enterprise Linux 6 libssh2 Red Hat Enterprise Linux 7 libssh2
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Hardened Images libssh2 1.11.1-10.1.hum1, libssh2 1.11.1-10.2.hum1
    fixed: vendor fix RHSA-2026:46535

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
4mo ago

Exploit prediction

0.29% chance of exploitation in the next 30 days, higher than 21% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/bikini/exploitarium/tree/main/libssh2-publickey-list-calc-poc referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
CNA 4.0 8.3 CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N
CNA 4.0 8.3 CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/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
OSV 3.1 6.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H

Affected packages

ecosystem package affected fixed in
julia LibSSH2_jll
<1.11.103+0
1.11.103+0

Affected products

  • libssh2 libssh2
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)

Classification

Weakness
  • CWE-908 Use of Uninitialized Resource

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.