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.
| Vendor | Product | Versions |
|---|---|---|
| libssh2 | libssh2 | 0 |
Downstream vendors/products affected by this vulnerability
| Vendor | Product | Source | Confidence |
|---|---|---|---|
| open source | libssh2 | cert_advisory | 90% |
Updated patch available to a new commit and added a new tag GHSA-R8MH-X5QV-7GG2.
Updated severity to CRITICAL and CVSS score to 9.2 for CVE-2026-55200.
Updated severity to HIGH, added CVSS score of 8.3, marked exploit as available and actively exploited, and added new CVE tags.
Updated severity to CRITICAL, noted that no exploit is available, and added CVE-2025-15661 as a tag.
Initial creation
