How severe is CVE-2026-58051?

CVE-2026-58051 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability high.

Is CVE-2026-58051 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (20th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-58051?

CVE-2026-58051 affects Libssh2. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-58051?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2026-58051 published?

CVE-2026-58051 was published on 2026-06-28 and last updated on 2026-06-30.

CVE-2026-58051

CVE-2026-58051 is a medium-severity vulnerability in Libssh2 with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-908.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v4: 8.3
EPSS exploit prediction: 0% (20th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-908
Affected product: Libssh2
Published: 2026-06-28
Last modified: 2026-06-30

Description

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.

Frequently asked questions

What is CVE-2026-58051?: 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.
How severe is CVE-2026-58051?: CVE-2026-58051 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability high.
Is CVE-2026-58051 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (20th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-58051?: CVE-2026-58051 affects Libssh2. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-58051?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-58051 published?: CVE-2026-58051 was published on 2026-06-28 and last updated on 2026-06-30.

References

Affected products (1)

cpe:2.3:a:libssh2:libssh2:*:*:*:*:*:*:*:*

More vulnerabilities in Libssh2

CVE-2019-3859 — Critical (CVSS 9.1): An out of bounds read flaw was discovered in libssh2 before 1.8.1 in the _libssh2_packet_require and…
CVE-2019-3857 — High (CVSS 8.8): An integer overflow flaw which could lead to an out of bounds write was discovered in libssh2 before 1.8.1 in the way…
CVE-2019-3856 — High (CVSS 8.8): An integer overflow flaw, which could lead to an out of bounds write, was discovered in libssh2 before 1.8.1 in the way…
CVE-2019-3855 — High (CVSS 8.8): An integer overflow flaw which could lead to an out of bounds write was discovered in libssh2 before 1.8.1 in the way…
CVE-2026-55200 — High (CVSS 8.1): libssh2 through 1.11.1, fixed in commit 7acf3df contains an out-of-bounds write vulnerability in ssh2_transport_read()…
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