Description
A Denial of Service (DoS) vulnerability exists in the Protobuf PHP library during the parsing of untrusted input. Maliciously structured messages—specifically those containing negative varints or deep recursion—can be used to crash the application, impacting service availability.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Protocol Buffers | Protobuf-php (Pecl) | < 5.34.0-RC1, < 4.33.6 | 5.34.0-RC1 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | protobuf | 3.21.12-16 | — |
| Debian 13 | protobuf | 3.21.12-11+deb13u1 | — |
| Debian 12 | protobuf | 3.21.12-3+deb12u1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | protobuf | 3.21.12-15ubuntu1.1 | USN-8943-1 |
| Ubuntu 25.10 | protobuf | No fix yet | — |
| Ubuntu 24.04 LTS | protobuf | 3.21.12-8.2ubuntu0.4 | USN-8943-1 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | protobuf | 25.3-7 | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Packagist | google/protobuf | < 4.33.6 | 4.33.6 | GHSA-p2gh-cfq4-4wjc |
Advisories 1
- USN-8943-1 protobuf vulnerability Ubuntu Security Notices (USN) · Oct 21, 2026