CVE-2026-44288 protobufjs: Overlong UTF-8 decoding
Attackers can bypass application-level byte checks by using overlong UTF-8 sequences in protobuf data, potentially evading security filters.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-44288?
CVE-2026-44288 is a medium-severity vulnerability in protobufjs protobuf.js, published on 13 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
protobufjs compiles protobuf definitions into JavaScript (JS) functions. Prior to 7.5.6 and 8.0.2, protobufjs includes a minimal UTF-8 decoder that accepted overlong UTF-8 byte sequences and decoded them to their canonical characters instead of replacing them. An attacker who can provide protobuf binary data decoded through the affected UTF-8 path may be able to bypass application-level checks that inspect raw bytes before protobuf string decoding. For example, bytes that do not contain certain ASCII characters could decode to strings containing those characters. This vulnerability is fixed in 7.5.6 and 8.0.2.
Weakness: CWE-176
Which versions are affected by CVE-2026-44288?
6 open source packages ship an affected version, including protobufjs and @protobufjs/utf8. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
protobufjs npm | All versions | 7.5.6 |
protobufjs npm | All versions | 7.5.6 |
protobufjs npm | From 8.0.0 | 8.0.2 |
protobufjs npm | From 8.0.0 | 8.0.2 |
@protobufjs/utf8 npm | All versions | 1.1.1 |
@protobufjs/utf8 npm | All versions | 1.1.1 |
Products include Protobufjs Project Protobufjs.
How do I fix CVE-2026-44288?
Upgrade protobufjs to a fixed version for your release line: 7.5.6 or 8.0.2.
Is CVE-2026-44288 being exploited?
There is no known exploitation of CVE-2026-44288 in the wild and no public exploit code.
Other vulnerabilities in protobufjs protobuf.js
- CVE-2023-36665 protobufjs Prototype Pollution vulnerability
- CVE-2026-41242 protobufjs has an arbitrary code execution issue
- CVE-2022-25878 Prototype Pollution
- CVE-2026-44291 protobufjs: Code generation gadget after prototype pollution
- CVE-2026-44293 protobufjs: Code injection through bytes field defaults in generated toObject code
Sources
Also known as CLEANSTART-2026-GG71544, CLEANSTART-2026-QH47034, CLSA-2026-1778805971, CLSA-2026-1780966319, CLSA-2026-1792161466, CLSA-2026-1792510240 and 19 more.