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Vulnerabilities

Vulnerability · CVE-2026-55200

libssh2 1.11.1, fixed in commit 97acf3d, contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field.

Published Jun 17, 2026 · catalog updated Oct 23, 2026 · libssh2 1.11.1, fixed in

Check if you run it

No confirmed exploitation is on record for CVE-2026-55200. EPSS is 4.02%. Act only if a listed version of libssh2 1.11.1, fixed in is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (libssh2 1.11.1, fixed in).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Critical9.2
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
4.02%
Remediation
Advisory link
Affected products
Alpine:v3.21 libssh2 · Alpine:v3.22 libssh2 · Alpine:v3.23 libssh2 · Alpine:v3.24 libssh2 · Alpine:v3.24 rust · cpe libssh2/libssh2

libssh2 1.11.1, fixed in commit 97acf3d, contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field. Remote attackers can send crafted SSH packets with excessively large packet_length values to corrupt heap memory and achieve remote code execution.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Alpine:v3.21 libssh20 → 1.11.1-r2
  • Alpine:v3.22 libssh20 → 1.11.1-r2
  • Alpine:v3.23 libssh20 → 1.11.1-r3
  • Alpine:v3.24 libssh20 → 1.11.1-r3
  • Alpine:v3.24 rust0 → 1.96.1-r0
  • cpe libssh2/libssh21.11.1

How to fix CVE-2026-55200

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-55200. EPSS is 4.02%. Act only if a listed version of libssh2 1.11.1, fixed in is installed.

Which versions are affected?

Compare what you have installed with 0 → 1.11.1-r2, 0 → 1.11.1-r3, 0 → 1.96.1-r0, 1.11.1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-680. EPSS 4.02%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Jun 17, 2026 · NIST NVD

    Detected

    libssh2 1.11.1, fixed in commit 97acf3d, contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field. Remote attackers can send crafted SSH packets with excessively large packet_length values to corrupt heap memory and achieve remote code execution.

  2. Oct 22, 2026 · NIST NVD

    Updated

    libssh2 1.11.1, fixed in commit 97acf3d, contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field. Remote attackers can send crafted SSH packets with excessively large packet_length values to corrupt heap memory and achieve remote code execution.

  3. Oct 23, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    libssh2 fixed in 1.11.1-r2; libssh2 fixed in 1.11.1-r2; libssh2 fixed in 1.11.1-r3; libssh2 fixed in 1.11.1-r3

  4. Oct 23, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    libssh2 fixed in 1.11.1-r2

  5. Oct 23, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    libssh2 fixed in 1.11.1-r3

  6. Oct 23, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    rust fixed in 1.96.1-r0

  7. Oct 23, 2026 · OpenSSF OSV / OSV Scanner

    Updated

    libssh2 1.11.1, fixed in commit 97acf3d, contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field. Remote attackers can send crafted SSH packets with excessively large packet_length values to corrupt heap memory and achieve remote code execution.

Sources

  • CVE.orgVulnerability recordCVE-2026-55200

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-55200

    30-day exploitation probability 4.02%

    first.org
  • NIST NVDVulnerability recordCVE-2026-55200

    libssh2 1.11.1, fixed in commit 97acf3d, contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field. Remote attackers can send crafted SSH packets with excessively large packet_length values to corrupt heap mem

    nvd.nist.gov
  • OpenSSF OSV / OSV ScannerPackage advisoryALPINE-CVE-2026-55200
    osv.dev
  • Trivy Vulnerability DBPackage advisoryALPINE-CVE-2026-55200

    libssh2 1.11.1, fixed in commit 97acf3d, contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field. Remote attackers can send crafted SSH packets with excessively large packet_length values to corrupt heap mem

    osv.dev

References

Freshness

Last verified in this catalog Oct 23, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.