What’s Vulnerable › Vulnerabilities

CVE-2025-15661: libssh2 - Heap Buffer Over-read via sftp_symlink() in sftp.c

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-18 · updated 2026-10-12
• Weakness: CWE-125

Description

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, triggering a heap buffer over-read of up to target_len minus one bytes due to the missing validation of available packet buffer size before the memcpy operation.

Affected products

• libssh2: through 1.11.1

References

• https://github.com/libssh2/libssh2/commit/2dae3024897e1898d389835151f4e9606227721d
• https://github.com/libssh2/libssh2/pull/1705
• https://github.com/libssh2/libssh2/pull/1717
• https://www.vulncheck.com/advisories/libssh2-heap-buffer-over-read-via-sftp-symlink-in-sftp-c

Get alerted when CVE-2025-15661 or the next vulnerability affects your stack