How severe is CVE-2020-16135?

CVE-2020-16135 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2020-16135 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (90th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-16135?

CVE-2020-16135 primarily affects Libssh. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-16135?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2020-16135 published?

CVE-2020-16135 was published on 2020-07-29 and last updated on 2026-06-17.

CVE-2020-16135

CVE-2020-16135 is a medium-severity vulnerability in Libssh with a CVSS 3.x base score of 5.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-476.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
CVSS v2: 4.3
EPSS exploit prediction: 4% (90th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-476
Affected product: Libssh
Published: 2020-07-29
Last modified: 2026-06-17

Description

libssh 0.9.4 has a NULL pointer dereference in tftpserver.c if ssh_buffer_new returns NULL.

Frequently asked questions

What is CVE-2020-16135?: libssh 0.9.4 has a NULL pointer dereference in tftpserver.c if ssh_buffer_new returns NULL.
How severe is CVE-2020-16135?: CVE-2020-16135 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2020-16135 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (90th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-16135?: CVE-2020-16135 primarily affects Libssh. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-16135?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-16135 published?: CVE-2020-16135 was published on 2020-07-29 and last updated on 2026-06-17.

References

Affected products (8)

cpe:2.3:a:libssh:libssh:0.9.4:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:20.04:*:*:*:lts:*:*:*
cpe:2.3:a:oracle:communications_cloud_native_core_policy:1.15.0:*:*:*:*:*:*:*

More vulnerabilities in Libssh

CVE-2018-10933 — Critical (CVSS 9.1): A vulnerability was found in libssh's server-side state machine before versions 0.7.6 and 0.8.4. A malicious client…
CVE-2019-14889 — High (CVSS 8.8): A flaw was found with the libssh API function ssh_scp_new() in versions before 0.9.3 and before 0.8.8. When the libssh…
CVE-2026-0966 — High (CVSS 8.2): A flaw was found in libssh. The API function `ssh_get_hexa()` is vulnerable to a denial of service when processing…
CVE-2025-5987 — High (CVSS 8.1): A flaw was found in libssh when using the ChaCha20 cipher with the OpenSSL library. If an attacker manages to exhaust…
CVE-2025-5318 — High (CVSS 8.1): A flaw was found in the libssh library in versions less than 0.11.2. An out-of-bounds read can be triggered in the…
CVE-2025-14821 — High (CVSS 7.8): A flaw was found in libssh. This vulnerability allows local man-in-the-middle attacks, security downgrades of SSH…

All CVEs affecting Libssh →

Other CWE-476 (NULL Pointer Dereference) vulnerabilities

CVE-2022-36648 — Critical (CVSS 10.0): The hardware emulation in the of_dpa_cmd_add_l2_flood of rocker device model in QEMU, as used in 7.0.0 and earlier,…
CVE-2020-14500 — Critical (CVSS 10.0): Secomea GateManager all versions prior to 9.2c, An attacker can send a negative value and overwrite arbitrary data.
CVE-2010-2495 — Critical (CVSS 10.0): The pppol2tp_xmit function in drivers/net/pppol2tp.c in the L2TP implementation in the Linux kernel before 2.6.34 does…
CVE-2026-46195 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: smb: client: validate dacloffset before building…
CVE-2026-31657 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: batman-adv: hold claim backbone gateways by…
CVE-2026-31436 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: dmaengine: idxd: fix possible wrong descriptor…

Browse all CWE-476 (NULL Pointer Dereference) vulnerabilities →