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

Published Jun 18, 2026
·
Updated

libssh2 - Heap Buffer Over-read via sftpsymlink() in sftp.c

Other sources

libssh2 through 1.11.1, fixed in commit 2dae302, contains an out-of-bounds heap read vulnerability in the sftpsymlink() 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 SSHFXPNAME response. Attackers can supply a linklen value larger than the actual packet data in SSHFXPNAME responses for SFTP READLINK and REALPATH operations, triggering a heap buffer over-read of up to targetlen minus one bytes due to the missing validation of available packet buffer size before the memcpy operation.

— Ubuntu

Affected Software

11 affected componentsFixes available
libssh2 libssh2<=1.11.1
Microsoft azl3 libssh2 1.11.1-3<1.11.1-4
1.11.1-4
Microsoft azl3 libssh2 1.11.1-4<1.11.1-4
1.11.1-4
libssh2 libssh2<=1.11.1
debian/libssh2<=1.10.0-3
1.10.0-3+deb12u11.11.1-1+deb13u21.11.1-1+deb13u11.11.1-6
alpine/chromium-rust<1.96.1-r0
1.96.1-r0
alpine/libssh2<1.11.1-r3
1.11.1-r3
alpine/libssh2<1.11.1-r3
1.11.1-r3
alpine/libssh2<1.11.1-r4
1.11.1-r4
alpine/libssh2<1.11.1-r4
1.11.1-r4
alpine/rust<1.96.1-r0
1.96.1-r0

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 1.11.1-4
  2. Upgrade

    Upgrade debian/libssh2 to a version that resolves this vulnerability.

    Fixed in 1.10.0-3+deb12u1Fixed in 1.11.1-1+deb13u2Fixed in 1.11.1-1+deb13u1Fixed in 1.11.1-6
  3. Upgrade

    Upgrade alpine/chromium-rust to a version that resolves this vulnerability.

    Fixed in 1.96.1-r0
  4. Upgrade

    Upgrade alpine/libssh2 to a version that resolves this vulnerability.

    Fixed in 1.11.1-r3
  5. Upgrade

    Upgrade alpine/libssh2 to a version that resolves this vulnerability.

    Fixed in 1.11.1-r4
  6. Upgrade

    Upgrade alpine/rust to a version that resolves this vulnerability.

    Fixed in 1.96.1-r0
  7. Upgrade

    Upgrade libssh2 to a version that resolves this vulnerability.

    Patch 2dae302

Event History

Jun 18, 2026
CVE Published
via Ubuntu·12:00 AM
Data Sourced
via Ubuntu·12:00 AM
RemedyDescriptionSeverityAffected Software
CVE Published
via MITRE·08:18 PM
Data Sourced
via MITRE·08:18 PM
DescriptionSeverityWeakness
Data Sourced
via NVD·09:16 PM
RemedyDescriptionSeverityWeaknessAffected Software
Data Sourced
via OSV·09:16 PM
DescriptionSeverityAffected Software
Jun 27, 2026
Data Sourced
via Microsoft·08:09 AM
DescriptionSeverityWeaknessAffected Software

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

Frequently Asked Questions

1

What is the severity of CVE-2025-15661?

CVE-2025-15661 has a medium severity rating of 6.5.

2

What is the risk level of CVE-2025-15661?

CVE-2025-15661 has a risk level of 45.

3

How do I fix CVE-2025-15661?

To fix CVE-2025-15661, you should update libssh2 to version 1.11.2 or later.

4

What kind of vulnerability is CVE-2025-15661?

CVE-2025-15661 is a heap buffer over-read vulnerability in the sftp_symlink() function.

5

Who can exploit CVE-2025-15661?

CVE-2025-15661 can be exploited by a malicious SSH server or a man-in-the-middle attacker.

Company

Resources

Contact

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