VulnerabilityPublished 24 Mar 2026

CVE-2026-4751: tmate · NULL Pointer Dereference

Affects tmateSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium : upgrade to 2.4.0 when convenient.

Data as of 26 Oct 2026, 11:42 UTC

CVSS 3.1 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 25% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.4.0

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 24 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade tmate-io/tmate and tmate to 2.4.0.

Affected software

Product	Affected	Fixed in
tmate-iotmate	Affected <2.4.0	Fixed in–
GitHubtmate-io/tmate`pkg:github/tmate-io/tmate`Other threats	Affected <2.4.0	Fixed in 2.4.0
GitHubtmate`pkg:github/tmate`Other threats	Affected <2.4.0	Fixed in 2.4.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Organizations should upgrade tmate installations to version 2.4.0 or later where this vulnerability is fixed. In the absence of an immediate patch, deploying network-level protections such as firewall rules to restrict access to tmate services to trusted IP addresses can reduce exposure. Monitoring tmate service logs and system stability metrics can help detect abnormal crashes indicative of exploitation attempts. Implementing redundancy or fallback remote access methods can mitigate operational impact during service interruptions. Security teams should also review and harden the environment where tmate runs, ensuring minimal privileges and isolation to limit potential damage from service crashes. Regularly updating and auditing remote collaboration tools is critical to maintaining secure and reliable operations.

Description

NULL Pointer Dereference vulnerability in tmate-io tmate.This issue affects tmate: before 2.4.0.

Impact

The primary impact of CVE-2026-4751 is the disruption of availability for users relying on tmate for remote terminal sharing. Organizations that use tmate for development, troubleshooting, or operational support may experience unexpected session terminations, leading to productivity loss and potential delays in critical tasks. While the vulnerability does not compromise data confidentiality or integrity, the denial of service can affect teams that depend on continuous remote access. In environments with automated workflows or critical incident response relying on tmate, this disruption could have cascading operational impacts. Since exploitation requires no authentication and no user interaction, attackers can easily trigger the crash remotely, increasing the risk of opportunistic denial of service attacks. However, the absence of known exploits in the wild suggests limited active targeting currently.

CWE-476NULL Pointer Dereference (opens in a new tab)
Base weaknessLikelihood of exploit: MediumCWE Top 25 (2025): #13OWASP Top 10 A10:2025: Mishandling of Exceptional Conditions (opens in a new tab)
The product dereferences a pointer that it expects to be valid but is NULL.
Implementation
For any pointers that could have been modified or provided from a function that can return NULL, check the pointer for NULL before use. When working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the check, and unlock when it has finished.
Requirements
Select a programming language that is not susceptible to these issues.
Implementation
Check the results of all functions that return a value and verify that the value is non-null before acting upon it.
OWASP Cheat Sheets
Logging (opens in a new tab)
Error Handling (opens in a new tab)
OWASP ASVS 4.0.3
V11.1.7 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/tmate-io/tmate/pull/328 (opens in a new tab)

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 24 Mar 2026, 15:04 UTC

WeaknessesCWE-476

Technical details

References

Community reviews

Related threats