VulnerabilityPublished 7 Mar 2026Updated 9 Mar 2026

CVE-2026-29781: BishopFox sliver · NULL Pointer Dereference

Affects BishopFox sliverSource CVE Database V5

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Public exploit available · CVSS 2.1 Low.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 4.0 base score

2.1Low

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

EPSS: 0.5% chance of exploitation in 30 days – higher than 45% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P

Base metrics

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Threat metrics

Exploit Maturity: POC

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

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, 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: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system 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 Vulnerable System 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 Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.
Exploit Maturity: POC: Based on threat intelligence sources each of the following must apply: · Proof-of-concept is publicly available · No knowledge of reported attempts to exploit this vulnerability · No knowledge of publicly available solutions used to simplify attempts to exploit the vulnerability

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 7 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
Public exploit code: GitHub proofs of concept
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), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 29 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), 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

Affected software

Product	Affected	Fixed in
BishopFoxsliver	Affected <=1.7.3	Fixed in–
GitHubbishopfox/sliver`pkg:github/bishopfox/sliver`Other threats	Affected <=1.7.3	Fixed in–

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

AI-suggested

Given the lack of publicly available patches, organizations should implement the following mitigations: 1) Restrict access to implant credentials and C2 server authentication tokens to minimize the risk of credential compromise. 2) Monitor Sliver server logs and network traffic for anomalous signed messages that omit nested fields or cause unexpected server crashes, enabling early detection of exploitation attempts. 3) Implement process supervision and automatic restart mechanisms (e.g., systemd, supervisor) for the Sliver server to reduce downtime caused by crashes. 4) Consider isolating the Sliver C2 server within segmented network environments to limit the blast radius of a forced restart. 5) Evaluate the use of the HTTP transport layer for implant communication where possible, as it includes panic recovery middleware that mitigates this vulnerability. 6) Maintain strict operational security around implant credential distribution and storage to prevent unauthorized post-authentication access. 7) Engage with BishopFox or the Sliver community for updates and patches addressing this issue. 8) Prepare incident response plans to quickly recover from forced Sliver server restarts to minimize operational impact.

Description

Sliver is a command and control framework that uses a custom Wireguard netstack. In versions from 1.7.3 and prior, a vulnerability exists in the Sliver C2 server's Protobuf unmarshalling logic due to a systemic lack of nil-pointer validation. By extracting valid implant credentials and omitting nested fields in a signed message, an authenticated actor can trigger an unhandled runtime panic. Because the mTLS, WireGuard, and DNS transport layers lack the panic recovery middleware present in the HTTP transport, this results in a global process termination. While requiring post-authentication access (a captured implant), this flaw effectively acts as an infrastructure "kill-switch," instantly severing all active sessions across the entire fleet and requiring a manual server restart to restore operations. At time of publication, there are no publicly available patches.

Impact

The primary impact of CVE-2026-29781 is a denial-of-service condition that causes the Sliver C2 server process to crash, severing all active implant sessions across the entire managed fleet. This disruption can halt ongoing operations relying on Sliver implants, affecting incident response, red team engagements, or adversary operations that use Sliver as a C2 framework. Organizations using Sliver for offensive security or red teaming may experience operational downtime and loss of control over deployed implants until manual intervention restarts the server. Although no direct data breach or privilege escalation is enabled by this flaw, the forced downtime can impair mission-critical activities and reduce situational awareness. The requirement for post-authentication access limits exploitation to actors who have already compromised implant credentials, reducing the likelihood of widespread abuse. However, a malicious insider or advanced attacker with access could weaponize this vulnerability as an infrastructure kill-switch to disrupt red team operations or defensive monitoring. The absence of automatic recovery mechanisms increases operational risk and response time. Overall, the impact is primarily operational disruption rather than data compromise or persistent system compromise.

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/BishopFox/sliver/security/advisories/GHSA-hx52-cv84-jr5v (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 14 Mar 2026, 19:56 UTC

Public exploits and detectionGitHub proofs of concept

WeaknessesCWE-476

Technical details

References

Community reviews

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