Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| libssh2 | libssh2 | 1.11.1 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | libssh2 | 1.11.1-4 | — |
| Debian 13 | libssh2 | 1.11.1-1+deb13u1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | libssh2 | 1.11.1-1ubuntu0.26.04.2 | — |
| Ubuntu 25.10 | libssh2 | 1.11.1-1ubuntu0.25.10.2 | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Hardened Images 1 | libssh2 +2 | 1.11.1-8.hum1 | RHSA-2026:29950 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | libssh2_org | 1.11.1-160000.4.1 | SUSE-SU-2026:22364-1 |
| SLES 16.0 | libssh2_org | 1.11.1-160000.4.1 | SUSE-SU-2026:22364-1 |
| SLE Micro 6.2 | libssh2_org | 1.11.1-160000.4.1 | SUSE-SU-2026:22284-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | libssh2_org | 1.11.1-3.1 | openSUSE-SU-2026:11109-1 |
| openSUSE Leap 16.0 | libssh2_org | 1.11.1-160000.4.1 | openSUSE-SU-2026:21057-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | libssh2 | 1.11.1-r3 | — |
| Alpine v3.24 | rust +1 | 1.96.1-r0 | — |
| Alpine v3.23 | libssh2 | 1.11.1-r3 | — |
| Alpine v3.22 | libssh2 | 1.11.1-r2 | — |
| Alpine v3.21 | libssh2 | 1.11.1-r2 | — |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | libssh2 | 1.11.1-3 | — |
| Azure Linux 3 | rust | No fix yet | — |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | libssh2 +2 | 1.11.1-r6 | — |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
GitHub 3 repositories
-
ashrafzaryouh/CVE-2026-55200 ★ 10 · Jun 23, 2026
CVE-2026-55200
-
xd20111/CVE-2026-55200 ★ 4 · Jun 29, 2026
CVE-2026-55200 - Critical libssh2 Remote Code Execution Vulnerability
-
kaleth4/CVE-2026-55200 ★ 0 · Jul 2, 2026
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 9
- NCSC-2026-0439 Kwetsbaarheden verholpen in Oracle PeopleSoft Enterprise NCSC-NL (Netherlands) · Oct 21, 2026
- WID-SEC-2026-4082 Oracle PeopleSoft: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 20, 2026
- RHSA-2026:29950 Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- WID-SEC-2026-1996 libssh2: Mehrere Schwachstellen BSI CERT-Bund (WID) · Aug 31, 2026
- SUSE-SU-2026:22364-1 Security update for libssh2_org SUSE / openSUSE Security Updates · Jul 2, 2026
- SUSE-SU-2026:22284-1 Security update for libssh2_org SUSE / openSUSE Security Updates · Jun 30, 2026
- openSUSE-SU-2026:21057-1 Security update for libssh2_org SUSE / openSUSE Security Updates · Jun 30, 2026
- NCSC-2026-0210 Kwetsbaarheden verholpen in libssh2 door libssh NCSC-NL (Netherlands) · Jun 24, 2026
- openSUSE-SU-2026:11109-1 libssh2-1-1.11.1-3.1 on GA media SUSE / openSUSE Security Updates · Jun 24, 2026
References
- Pull Request issue-tracking patch
- Patch Commit patch
- https://www.vulncheck.com/advisories/libssh2-out-of-bounds-write-via-unchecked-packet-length-in-transport-c third-party-advisory