PatchTheCVECVE-2025-15661: libssh2 through 1.11.1, fixed in commit 2dae302, contains an out-of-bounds heap read vulnerability in the sftp
CVE-2025-15661 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, fixed in commit 2dae302, contains an out-of-bounds heap read vulnerability in the sftp_symlink() function in src/sftp.c that allows a malicious SSH server or man-in-the-middle attacker to disclose heap memory contents or cause a crash by sending a crafted SSH_FXP_NAME response. Attackers can supply a link_len value larger than the actual packet data in SSH_FXP_NAME responses for SFTP READLINK and REALPATH operations, trigg
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 | 0.6% (top 49%) |
| CISA exploited list | No |
| Weakness | CWE-125 |
| Published | 2026-06-18 |
| Last modified | 2026-10-12 |
Last updated 2026-10-12 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
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-2025-15661?
libssh2: upgrade to newer than 1.11.1. Exact commands for each OS are on this page.
Is CVE-2025-15661 being exploited?
CVE-2025-15661 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-2025-15661 affect?
CVE-2025-15661 affects libssh2. Severity is medium (CVSS 6.5). libssh2 through 1.11.1, fixed in commit 2dae302, contains an out-of-bounds heap read vulnerability in the sftp_symlink() function in src/sftp.c that allows a malicious SSH server or man-in-the-middle attacker to disclose heap memory content
How urgent is CVE-2025-15661?
Priority 40/100. 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-2026-58051 MEDIUM 6.5 UPGRADE libssh2 through 1.11.1 grows its publickey list with SSH2_REALLOC but does not zero-initialize new entries bef
- 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(
- CVE-2026-66032 HIGH 8.8 UPGRADE libssh2 through 1.11.1, fixed in commit 5e47761, contains a double-free vulnerability in the sftp_open() funct
- CVE-2026-66033 HIGH 7.5 UPGRADE libssh2 through 1.11.1, fixed in commit a2ed82d, contains a pre-authentication integer underflow vulnerability