VulnerabilityPublished 27 Feb 2026Updated 2 Mar 2026

CVE-2026-28407: chainguard-dev malcontent · Improper Check or Handling of Exceptional Conditions

Affects chainguard-dev malcontentSource CVE Database V5

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Not known to be exploited · CVSS 6.9 Medium : upgrade to 1.21.0 when convenient.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 4.0 base score

6.9Medium

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 35% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.21.0

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

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

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: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
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: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within 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.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 27 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 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

Upgrade malcontent and chainguard-dev/malcontent to 1.21.0.

Affected software

Product	Affected	Fixed in
chainguard-devmalcontent	Affected <1.21.0	Fixed in 1.21.0
GitHubchainguard-dev/malcontent`pkg:github/chainguard-dev/malcontent`Other threats	Affected <1.21.0	Fixed in 1.21.0

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

AI-suggested

To mitigate CVE-2026-28407, organizations should promptly upgrade malcontent to version 1.21.0 or later, which includes the fix that preserves nested archives failing extraction for best-effort scanning. Additionally, organizations should implement the following specific measures: 1) Integrate multiple layers of supply-chain security tools to complement malcontent, reducing reliance on a single detection mechanism. 2) Configure malcontent to generate detailed logs and alerts on extraction failures to enable manual review of suspicious archives. 3) Employ sandboxing or isolated environments to manually analyze nested archives that fail automated extraction. 4) Regularly audit and verify the integrity of software artifacts and dependencies beyond automated scanning tools. 5) Maintain up-to-date YARA rules and threat intelligence feeds to improve detection capabilities. 6) Establish incident response procedures specifically for supply-chain compromise scenarios to quickly address any suspicious findings. These steps will help reduce the risk of malicious content evading detection due to extraction failures and improve overall supply-chain security posture.

Description

malcontent is software for discovering supply-chain compromises through context, differential analysis, and YARA. Prior to version 1.21.0, malcontent would remove nested archives which failed to extract which could potentially leave malicious content. A better approach is to preserve these archives so that malcontent can attempt a best-effort scan of the archive bytes. Version 1.21.0 fixes the issue.

Impact

The primary impact of CVE-2026-28407 is on the integrity and reliability of supply-chain compromise detection performed by malcontent. By removing nested archives that fail to extract, malcontent versions prior to 1.21.0 risk missing malicious content embedded within these archives. This can lead to false negatives in threat detection, allowing attackers to bypass security controls and introduce malicious artifacts into software supply chains undetected. For organizations that depend on malcontent for supply-chain security, this vulnerability could result in compromised software components being trusted and deployed, increasing the risk of downstream attacks such as code injection, backdoors, or data exfiltration. Since malcontent is used to analyze software artifacts, the scope of affected systems includes any environment where malcontent is deployed for supply-chain security, including software development pipelines, continuous integration/continuous deployment (CI/CD) systems, and security auditing platforms. The vulnerability does not directly affect availability or confidentiality but undermines the integrity of the detection process, which is critical for maintaining secure software supply chains. Although no exploits are known in the wild, the ease of exploitation is moderate given that no authentication or user interaction is required, and the attack vector is network-based. Organizations failing to update may face increased risk of undetected supply-chain compromises.

CWE-703Improper Check or Handling of Exceptional Conditions (opens in a new tab)
Pillar weaknessOWASP Top 10 A10:2025: Mishandling of Exceptional Conditions (opens in a new tab)
The product does not properly anticipate or handle exceptional conditions that rarely occur during normal operation of the product.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
OWASP Cheat Sheets
Logging (opens in a new tab)
Error Handling (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 7 Mar 2026, 21:18 UTC

WeaknessesCWE-703

Technical details

References

Community reviews

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