CVE-2026-58051: libssh2 through 1.11.1 grows its publickey list with SSH2_REALLOC but does not zero-initialize new entries bef

Q: How do I fix CVE-2026-58051?

libssh2: upgrade to newer than 1.11.1. Exact commands for each OS are on this page.

Q: Is CVE-2026-58051 being exploited?

CVE-2026-58051 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-58051 affect?

CVE-2026-58051 affects libssh2. Severity is medium (CVSS 6.5). 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 uninit

Q: How urgent is CVE-2026-58051?

Priority 33/100. Remotely exploitable, no login, no user action

Routine

MEDIUM 6.5REMOTEUPGRADE

CVE-2026-58051 is a medium-severity flaw (CVSS 6.5) affecting libssh2. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 80%)
CISA exploited list	No
Weakness	CWE-908
Published	2026-06-28
Last modified	2026-10-25

Publisher (CNA): VulnCheck · Vendor: libssh2

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-28 02:16 UTCPublished CVE record published
2026-10-25 17:10 UTCUpdated Record last modified

libssh2 libssh2 UPGRADE

Affected: <= 1.11.1

Fixed in: newer than 1.11.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy libssh2 || rpm -q libssh2 || libssh2 --version

2. UPGRADE to newer than 1.11.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade libssh2

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade libssh2

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-58051?

libssh2: upgrade to newer than 1.11.1. Exact commands for each OS are on this page.

Is CVE-2026-58051 being exploited?

CVE-2026-58051 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-58051 affect?

CVE-2026-58051 affects libssh2. Severity is medium (CVSS 6.5). 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 uninit

How urgent is CVE-2026-58051?

Priority 33/100. Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-58050 HIGH 7.0 UPGRADE libssh2 through 1.11.1 reads an attacker-controlled 32-bit attribute count from a publickey-subsystem response
CVE-2026-55200 HIGH 8.1 DOWNGRADE libssh2 1.11.1, fixed in commit 97acf3d, contains an out-of-bounds write vulnerability in ssh2_transport_read(

References

← Back to latest CVEs