VulnerabilityPublished 13 May 2026

CVE-2026-44288: protobufjs protobuf.js · Improper Handling of Unicode Encoding

Affects protobufjs protobuf.jsSource CVE Database V5

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Not known to be exploited · CVSS 5.3 Medium : upgrade to 8.0.2 or 7.5.6 when convenient.

Data as of 30 Oct 2026, 11:52 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 22% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 8.0.2, 7.5.6, 8.0.3

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

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

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: 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 on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 13 May 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 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

Upgrade protobuf.js to 8.0.2 or 7.5.6; protobufjs/protobuf.js to 8.0.3 or 7.5.6.

Affected software

Product	Affected	Fixed in
protobufjsprotobuf.js	Affected >=8.0.0 <8.0.2	Fixed in 8.0.2
protobufjsprotobuf.js	Affected <7.5.6	Fixed in 7.5.6
npmprotobufjs/protobuf.js`pkg:npm/protobufjs/protobuf.js`Other threats	Affected <7.5.6 >=8.0.0 <8.0.3	Fixed in 7.5.6 8.0.3

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

AI-suggested

Upgrading protobuf.js to version 7.5.6 or later (for the 7.x series) or to version 8.0.2 or later (for the 8.x series) resolves this vulnerability. Patch status is not explicitly stated in the vendor advisory, but the description confirms the issue is fixed in these versions. Users should update to these fixed versions to mitigate the risk. No additional mitigation steps are indicated.

Description

protobuf.js versions prior to 7.5.6 and between 8.0.0 and 8.0.2 contain a vulnerability in their UTF-8 decoding implementation. The minimal UTF-8 decoder accepted overlong UTF-8 byte sequences and decoded them to canonical characters instead of replacing them. This behavior may allow an attacker to bypass application-level checks that inspect raw bytes before protobuf string decoding.

Impact

This vulnerability allows an attacker who can supply protobuf binary data to bypass application-level checks that inspect raw bytes before protobuf string decoding. This could lead to integrity issues where the application processes strings containing unexpected characters, potentially affecting application logic or security controls relying on raw byte inspection. There is no impact on confidentiality or availability. No known exploits have been reported in the wild.

CWE-176Improper Handling of Unicode Encoding (opens in a new tab)
Variant weakness
The product does not properly handle when an input contains Unicode encoding.
Architecture and Design · Input Validation
Avoid making decisions based on names of resources (e.g. files) if those resources can have alternate names.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Implementation · Input Validation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174).
OWASP Cheat Sheets
Unvalidated Redirects and Forwards (opens in a new tab)
XML Security (opens in a new tab)
XML External Entity Prevention (opens in a new tab)
File Upload (opens in a new tab)
Input Validation (opens in a new tab)
OWASP ASVS 4.0.3
V5.3.2 (opens in a new tab)
V1.5.1 (opens in a new tab)
Attack patterns
Using Unicode Encoding to Bypass Validation Logic (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/protobufjs/protobuf.js/security/advisories/GHSA-q6x5-8v7m-xcrf (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 20 May 2026, 19:10 UTC

WeaknessesCWE-176

Technical details

References

Community reviews

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