VulnerabilityPublished 3 Mar 2026

CVE-2026-3463: xlnt · Heap-based Buffer Overflow

Affects xlntSource CVE Database V5

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Public exploit available · CVSS 4.8 Medium.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 4.0 base score

4.8Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 12% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:L/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: Local
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: Local: The vulnerable system is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).
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 3 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
CVSS exploit maturity: proof of concept public
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), CVSS vector, 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
xlnt-communityxlnt	Affected =1.6.0 =1.6.1	Fixed in–
GitHubxlnt-community/xlnt`pkg:github/xlnt-community/xlnt`Other threats	Affected =1.6.0 =1.6.1	Fixed in–

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-2026-3463, organizations should immediately apply the vendor-provided patch (Patch 147) that addresses the heap-based buffer overflow in xlnt versions 1.6.0 and 1.6.1. If patching is not immediately possible, restrict local access to systems running applications that use xlnt to trusted users only. Implement strict user account controls and limit the ability of local users to execute or influence xlnt-based processes. Conduct code reviews and testing for any custom software that embeds xlnt to ensure it does not expose the vulnerable functionality to untrusted inputs. Employ runtime protections such as heap memory protection mechanisms (e.g., ASLR, DEP) to reduce exploitation success. Monitor local system logs for unusual crashes or behavior related to xlnt processes. Finally, maintain an inventory of software components to identify all instances of xlnt usage and prioritize patching accordingly.

Description

A weakness has been identified in xlnt-community xlnt up to 1.6.1. Impacted is the function xlnt::detail::binary_writer::append of the file source/detail/binary.hpp of the component Compound Document Parser. This manipulation causes heap-based buffer overflow. The attack can only be executed locally. The exploit has been made available to the public and could be used for attacks. Patch name: 147. It is suggested to install a patch to address this issue.

Impact

The primary impact of CVE-2026-3463 is the potential for local attackers to cause memory corruption through a heap-based buffer overflow, which can lead to application crashes (denial of service) or potentially arbitrary code execution if exploited successfully. While the attack requires local access and limited privileges, the availability of a public exploit increases the likelihood of exploitation in environments where multiple users share access or where local user accounts are less restricted. Organizations using xlnt in desktop applications, automated workflows, or development environments may face risks of service disruption or compromise of the affected application. However, the vulnerability does not allow remote exploitation, limiting its impact to local threat scenarios. The confidentiality, integrity, and availability of systems using xlnt could be affected if attackers leverage this flaw to escalate privileges or execute malicious code within the local context. Overall, the impact is medium but could be significant in multi-user or shared environments where local access is easier to obtain.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 3 Mar 2026, 12:32 UTC

Technical details

References

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