CVE-2025-15661
MediumCVSS 6.5Exploitation Probability (EPSS)
Low risk18th percentile — higher than 18% of all known CVEs
Summary
The vulnerability in libssh2 up to version 1.11.1 (fixed in commit 2dae302) allows an out-of-bounds heap read in the sftp_symlink() function in src/sftp.c. A malicious SSH server or man-in-the-middle attacker can disclose heap memory contents or cause a crash by sending a crafted SSH_FXP_NAME response.
Risk Assessment
An attacker can read sensitive data from heap memory (e.g., keys, passwords) or cause a denial of service (crash) in applications using libssh2.
Recommendation
Update libssh2 to a version containing commit 2dae302 or later. If an update is not possible, restrict trust to SSH servers and use transport encryption (e.g., TLS) to hinder MITM attacks.
Original NVD description (English source)
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.