High Memory corruption exploit reference

CVE-2020-24659 — NULL Pointer Dereference in Canonical Ubuntu Linux

An issue was discovered in GnuTLS before 3.6.15. A server can trigger a NULL pointer dereference in a TLS 1.3 client if a no_renegotiation alert is sent with unexpected timing, and then an invalid second handshake occurs. The crash happens in the application's error handling path, where the gnutls_deinit function is called after detecting a handshake failure.

Published Sep 4, 2020 · Updated Oct 14, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: mitre

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 3.8% (30-day exploitation probability)+13
Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

3.83%

ahead of 90% of scored CVEs · Oct 14, 2026

Affects

Canonical

Ubuntu Linux and 3 more

CVSS base

7.5

High · 1 source(s)

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Canonical Ubuntu Linux, Fedoraproject Fedora, Gnu Gnutls…).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Canonical	Ubuntu Linux	version 20.04	Vulnerable	NIST National Vulnerability Database
Fedoraproject	Fedora	version 32version 33	Vulnerable	NIST National Vulnerability Database
Gnu	Gnutls	< 3.6.15	Vulnerable	NIST National Vulnerability Database
Opensuse	Leap	version 15.1version 15.2	Vulnerable	NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
7.5	CVSS 3.1	High	3.9	3.6	nvd@nist.gov via NIST National Vulnerability Database
5.0	CVSS 2.0	Medium	10.0	2.9	nvd@nist.gov via NIST National Vulnerability Database

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-476 · NULL Pointer Dereference

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.

web/proxy/WAF logsnetwork IDS/IPSendpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

2026
Record published
Oct 14, 2026
CVSS changed · 7.5
Oct 14, 2026 · NIST National Vulnerability Database
Source status changed · → Modified
Oct 14, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 14, 2026 · NIST National Vulnerability Database
2020
CVE published
Sep 4, 2020 · mitre

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 14, 2026 – Oct 14, 2026

References

10 on the record

www.gnutls.org/security-new.html
Vendor Advisory, x_refsource_MISC, NIST National Vulnerability Database
lists.opensuse.org/opensuse-security-announce/2020-10/msg00054.html
Mailing List, Third Party Advisory, vendor-advisory, x_refsource_SUSE, NIST National Vulnerability Database
usn.ubuntu.com/4491-1/
Third Party Advisory, vendor-advisory, x_refsource_UBUNTU, NIST National Vulnerability Database
cert-portal.siemens.com/productcert/html/ssa-398330.html
NIST National Vulnerability Database
gitlab.com/gnutls/gnutls/-/issues/1071
Exploit, Issue Tracking, Third Party Advisory, x_refsource_MISC, NIST National Vulnerability Database
lists.opensuse.org/opensuse-security-announce/2020-10/msg00060.html
Mailing List, Third Party Advisory, vendor-advisory, x_refsource_SUSE, NIST National Vulnerability Database
security.netapp.com/advisory/ntap-20200911-0006/
Third Party Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AWN5
vendor-advisory, x_refsource_FEDORA, NIST National Vulnerability Database
security.gentoo.org/glsa/202009-01
Third Party Advisory, vendor-advisory, x_refsource_GENTOO, NIST National Vulnerability Database
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/62BU
vendor-advisory, x_refsource_FEDORA, NIST National Vulnerability Database

Elsewhere on this site

Canonical
every CVE for this vendor

Memory corruption
same class

CWE-476
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-54231 Abrt: unsanitized systemd journal content written to dump directory files enables content injection Jun 13, 2026
High CVE-2026-54230 Abrt: event handler scripts follow symlinks when writing output files, allowing arbitrary file overwrites Jun 13, 2026
Low CVE-2026-47337 NULL pointer dereference in Ubuntu Linux AppArmor IPv4/IPv6 socket mediation May 28, 2026
Low CVE-2026-47336 Use of uninitialized value in Ubuntu Linux AppArmor IPv4/IPv6 socket mediation rules May 28, 2026
Medium CVE-2026-47334 Deadlock or kernel panic in Ubuntu Linux AppArmor notification handling May 28, 2026
Medium CVE-2026-47335 NULL pointer dereference in Ubuntu Linux AppArmor notification handling May 28, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No CISA SSVC assessment.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2020-24659 is "NULL Pointer Dereference in Canonical Ubuntu Linux", rated High. It affects Ubuntu Linux (Canonical); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.5 describes technical severity. EPSS 3.83% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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