CVE-2025-5449
Libssh: integer overflow in libssh sftp server packet length validation leading to denial of service
A flaw was found in the SFTP server message decoding logic of libssh. The issue occurs due to an incorrect packet length check that allows an integer overflow when handling large payload sizes on 32-bit systems. This issue leads to failed memory allocation and causes the server process to crash, resulting in a denial of service.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
6.5
Libssh: integer overflow in libssh sftp server packet length validation leading to denial of service
A flaw was found in the SFTP server message decoding logic of libssh. The issue occurs due to an incorrect packet length check that allows an integer overflow when handling large payload sizes on 32-bit systems. This issue leads to failed memory allocation and causes the server process to crash, resulting in a denial of service.
- Record
CVE-2025-5449- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-190
- Updated
- 2026-11-05
EUVDEUVD-2025-22738
6.5
A flaw was found in the SFTP server message decoding logic of libssh. The issue occurs due to an incorrect packet length check that allows an integer overflow when handling large payload sizes on 32-bit systems. This issue leads to failed memory allocation and causes the server process to crash, resulting in a denial of service.
- Record
EUVD-2025-22738- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-05
GitHub AdvisoriesGHSA-q9x7-4rf7-4xq2
4.3
A flaw was found in the SFTP server message decoding logic of libssh. The issue occurs due to an...
A flaw was found in the SFTP server message decoding logic of libssh. The issue occurs due to an incorrect packet length check that allows an integer overflow when handling large payload sizes on 32-bit systems. This issue leads to failed memory allocation and causes the server process to crash, resulting in a denial of service.
- Record
GHSA-q9x7-4rf7-4xq2- CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L - Weakness
- CWE-190
- Updated
- 2026-11-02
NVD
6.5
A flaw was found in the SFTP server message decoding logic of libssh. The issue occurs due to an incorrect packet length check that allows an integer overflow when handling large payload sizes on 32-bit systems. This issue leads to failed memory allocation and causes the server process to crash, resulting in a denial of service.
- Record
CVE-2025-5449- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-190
- Updated
- 2026-11-05
OSVALPINE-CVE-2025-5449
6.5
A flaw was found in the SFTP server message decoding logic of libssh. The issue occurs due to an incorrect packet length check that allows an integer overflow when handling large payload sizes on 32-bit systems. This issue leads to failed memory allocation and causes the server process to crash, resulting in a denial of service.
- Record
ALPINE-CVE-2025-5449- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-03
OSVBELL-CVE-2025-5449
6.5
- Record
BELL-CVE-2025-5449- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
Show 7 moreShow less
OSV
6.5
Libssh: integer overflow in libssh sftp server packet length validation leading to denial of service
A flaw was found in the SFTP server message decoding logic of libssh. The issue occurs due to an incorrect packet length check that allows an integer overflow when handling large payload sizes on 32-bit systems. This issue leads to failed memory allocation and causes the server process to crash, resulting in a denial of service.
- Record
CVE-2025-5449- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-190
- Updated
- 2026-11-07
OSVDEBIAN-CVE-2025-5449
6.5
A flaw was found in the SFTP server message decoding logic of libssh. The issue occurs due to an incorrect packet length check that allows an integer overflow when handling large payload sizes on 32-bit systems. This issue leads to failed memory allocation and causes the server process to crash, resulting in a denial of service.
- Record
DEBIAN-CVE-2025-5449- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVJLSEC-2025-100
6.5
A flaw was found in the SFTP server message decoding logic of libssh
A flaw was found in the SFTP server message decoding logic of libssh. The issue occurs due to an incorrect packet length check that allows an integer overflow when handling large payload sizes on 32-bit systems. This issue leads to failed memory allocation and causes the server process to crash, resulting in a denial of service.
- Record
JLSEC-2025-100- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2025-5449
6.5
A flaw was found in the SFTP server message decoding logic of libssh. The issue occurs due to an incorrect packet length check that allows an integer overflow when handling large payload sizes on 32-bit systems. This issue leads to failed memory allocation and causes the server process to crash, resulting in a denial of service.
- Record
UBUNTU-CVE-2025-5449- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVMGASA-2026-0189 No score
Updated libssh packages fix security vulnerabilities
CVE-2025-4877 Write beyond bounds in binary to base64 conversion functions CVE-2025-4878 Use of uninitialized variable in privatekey_from_file() CVE-2025-5318 Likely read beyond bounds in sftp server handle management CVE-2025-5351 Double free in functions exporting keys CVE-2025-5372 ssh_kdf() returns a success code on certain failures CVE-2025-5449 Likely read beyond bounds in sftp server message decoding CVE-2025-5987 Invalid return code for chacha20 poly1305 with OpenSSL backend
- Record
MGASA-2026-0189- Updated
- 2026-11-02
OSVopenSUSE-SU-2025:15243-1 No score
libssh-config-0.11.2-1.1 on GA media
These are all security issues fixed in the libssh-config-0.11.2-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2025:15243-1- Updated
- 2026-11-02
OSVUSN-7619-1 No score
libssh vulnerabilities
Ronald Crane discovered that libssh incorrectly handled certain base64 conversions. An attacker could use this issue to cause libssh to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2025-4877)
Ronald Crane discovered that libssh incorrectly handled the privatekey_from_file() function. An attacker could use this issue to cause libssh to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2025-4878)
Ronald Crane discovered that libssh incorrectly handled certain memory operations in the sftp server. An attacker could possibly use this issue to cause libssh to crash, resulting in a denial of service. (CVE-2025-5318, CVE-2025-5449)
Ronald Crane discovered that libssh incorrectly handled exporting keys. An attacker could possibly use this issue to cause libssh to crash, resulting in a denial of service. This issue only affected Ubuntu 24.04 LTS, Ubuntu 24.10, and Ubuntu 25.04. (CVE-2025-5351)
Ronald Crane discovered that libssh incorrectly handled the ssh_kdf() function. An attacker could use this issue to cause libssh to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2025-5372)
Ronald Crane discovered that libssh incorrectly handled the ChaCha20 cipher. An attacker could possibly use this issue to cause libssh to use partially initialized cypher content. This issue only affected Ubuntu 24.04 LTS, Ubuntu 24.10, and Ubuntu 25.04. (CVE-2025-5987)
- Record
USN-7619-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
libsshAlpine:v3.22 |
before 0.11.2-r0 | 0.11.2-r0 |
libsshAlpine:v3.23 |
before 0.11.2-r0 | 0.11.2-r0 |
libsshAlpine:v3.24 |
before 0.11.2-r0 | 0.11.2-r0 |
libsshAlpaquita:25 |
0.11.1-r0 up to 0.11.2-r0 | 0.11.2-r0 |
libsshAlpaquita:stream |
0.11.1-r0 up to 0.11.2-r0 | 0.11.2-r0 |
libsshDebian:13 |
before 0.11.2-1 | 0.11.2-1 |
libsshDebian:14 |
before 0.11.2-1 | 0.11.2-1 |
libssh_jllJulia |
0.11.0+0 up to 0.11.3+0 | 0.11.3+0 |
libsshMageia:9 From an advisory covering 7 CVEs |
before 0.10.6-1.1.mga9 | 0.10.6-1.1.mga9 |
libsshUbuntu:22.04:LTS From an advisory covering 7 CVEs |
before 0.9.6-2ubuntu0.22.04.4, plus listed versions 0.9.6-10.9.6-1build10.9.6-20.9.6-2build10.9.6-2ubuntu0.22.04.10.9.6-2ubuntu0.22.04.20.9.6-2ubuntu0.22.04.3 |
0.9.6-2ubuntu0.22.04.4 |
libsshUbuntu:24.04:LTS From an advisory covering 7 CVEs |
before 0.10.6-2ubuntu0.1, plus listed versions 0.10.5-3ubuntu10.10.5-3ubuntu20.10.6-20.10.6-2build10.10.6-2build2 |
0.10.6-2ubuntu0.1 |
libsshopenSUSE:Tumbleweed From an advisory covering 7 CVEs |
before 0.11.2-1.1 | 0.11.2-1.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected | EUVD, NVD, OSV | |
| facts | CVE List | |
| affected, aliases, references | OSV | |
| affected | ||
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2025-5449 is a medium vulnerability (CVSS 6.5) in Libssh, published June 25, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.03%, the 63rd percentile. Fixed in libssh 0.11.2-r0.
References
access.redhat.com/security/cve/CVE-2025-5449
bugzilla.redhat.com/show_bug.cgi?id=2369705
git.libssh.org/projects/libssh.git/commit?h=stable-0.11&id=261612179f740bc62ba363d98b3bd5e5573a811f
git.libssh.org/projects/libssh.git/commit?h=stable-0.11&id=3443aec90188d6aab9282afc80a81df5ab72c4da
git.libssh.org/projects/libssh.git/commit?h=stable-0.11&id=5504ff40515439a5fecbb17da7483000c4d12eb7
git.libssh.org/projects/libssh.git/commit?h=stable-0.11&id=78485f446af9b30e37eb8f177b81940710d54496
Show 29 moreShow less
git.libssh.org/projects/libssh.git/commit?h=stable-0.11&id=f79ec51b7fd519dbc5737a7ba826e3ed093f6ceb
libssh.org/security/advisories/CVE-2025-5449.txt
nvd.nist.gov/vuln/detail/CVE-2025-5449
github.com/advisories/GHSA-q9x7-4rf7-4xq2
security.alpinelinux.org/vuln/CVE-2025-5449
docs.bell-sw.com/security/cves/CVE-2025-5449
access.redhat.com/downloads/content/package-browser
libssh.org
github.com/CVEProject/cvelistV5/tree/main/cves/2025/5xxx/CVE-2025-5449.json
security-tracker.debian.org/tracker/CVE-2025-5449
advisories.mageia.org/MGASA-2026-0189.html
bugs.mageia.org/show_bug.cgi?id=34405
openwall.com/lists/oss-security/2025/06/27/2
ubuntu.com/security/CVE-2025-5449
cve.org/CVERecord?id=CVE-2025-5449
ubuntu.com/security/notices/USN-7619-1
ubuntu.com/security/CVE-2025-4877
ubuntu.com/security/CVE-2025-4878
ubuntu.com/security/CVE-2025-5318
ubuntu.com/security/CVE-2025-5351
ubuntu.com/security/CVE-2025-5372
ubuntu.com/security/CVE-2025-5987
suse.com/security/cve/CVE-2025-4877
suse.com/security/cve/CVE-2025-4878
suse.com/security/cve/CVE-2025-5318
suse.com/security/cve/CVE-2025-5351
suse.com/security/cve/CVE-2025-5372
suse.com/security/cve/CVE-2025-5449
suse.com/security/cve/CVE-2025-5987