VulnerabilityPublished 8 Mar 2026Updated 10 Mar 2026

CVE-2026-3707: MrNanko webp4j · Integer Overflow

Affects MrNanko webp4jSource CVE Database V5

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Public exploit available · CVSS 4.8 Medium.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score

4.8Medium

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 1% 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:L/VI:L/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: Low
Vulnerable system integrity: Low
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: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to 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: 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 8 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 30 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
MrNankowebp4j	Affected 1.0 – 1.3 4 affected builds	Fixed in–
GitHubmrnanko/webp4j`pkg:github/mrnanko/webp4j`Other threats	Affected 1.0 – 1.3 4 affected builds	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-2026-3707, organizations should promptly apply the official patch identified by commit 89771b201c66d15d29e4cc016d8aae82b6a5fbe1 that corrects the integer overflow in the DecodeGifFromMemory function. Additionally, restrict local access to systems running webp4j to trusted users only, minimizing the risk of exploitation by unprivileged users. Employ application whitelisting and endpoint protection to detect and prevent execution of unauthorized code locally. Conduct code audits and static analysis on any custom software embedding webp4j to ensure no unsafe usage of the vulnerable function remains. Monitor system logs for unusual crashes or behavior indicative of exploitation attempts. If possible, isolate or sandbox applications using webp4j to limit the impact of potential memory corruption. Finally, maintain up-to-date backups to recover from any denial-of-service or data integrity incidents resulting from exploitation.

Description

A vulnerability was identified in MrNanko webp4j up to 1.3.x. The affected element is the function DecodeGifFromMemory of the file src/main/c/gif_decoder.c. Such manipulation of the argument canvas_height leads to integer overflow. Local access is required to approach this attack. The exploit is publicly available and might be used. The name of the patch is 89771b201c66d15d29e4cc016d8aae82b6a5fbe1. It is advisable to implement a patch to correct this issue.

Impact

The integer overflow vulnerability in webp4j can lead to memory corruption, which may cause application crashes or potentially allow an attacker to execute arbitrary code with the privileges of the affected process. Since exploitation requires local access, the risk is primarily to systems where untrusted users have local accounts or can execute code locally. The impact spans confidentiality, integrity, and availability, as memory corruption can be leveraged to read sensitive data, modify program behavior, or cause denial of service. Organizations using webp4j in development environments, embedded systems, or local applications are at risk. The availability of public exploit code increases the likelihood of exploitation attempts. However, the lack of remote attack vector limits the threat to local environments. Failure to patch could lead to privilege escalation or persistent compromise in multi-user systems. The medium CVSS score reflects the balance between potential impact and limited attack vector.

References

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