CVE-2025-15661
CWE-125Published: June 18, 2026· Updated: Jun 22, 2026
Official 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.
Technical Analysis
CVE-2025-15661 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.
A successful exploit results in availability disruption (denial of service), with a CVSS base score of 6.5.
CVSS v3.1 Vector Breakdown
Exploit & PoC Resources
All References (4)
Quick Facts
Related CVEs (CWE-125)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2025-15661 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts