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CVE

CVE-2026-6409

Protobuf: Denial of Service issue through malicious messages containing negative varints or deep recursion
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CVE

CVE-2026-6409

Protobuf: Denial of Service issue through malicious messages containing negative varints or deep recursion

Impact

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.

Patches

Patches have been released to 5.34.0-RC1 and 4.33.6.

Package Versions Affected

Package Version
patch Availability
No items found.

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CVSS Version

Severity
Base Score
CVSS Version
Score Vector
C
H
U
7.1
-
4.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
C
H
U
0
-
C
H
U
-

Related Resources

No items found.

References

https://github.com/protocolbuffers/protobuf/security/advisories/GHSA-p2gh-cfq4-4wjc, https://nvd.nist.gov/vuln/detail/CVE-2026-6409, https://github.com/protocolbuffers/protobuf/issues/24159, https://github.com/protocolbuffers/protobuf/issues/25067, https://github.com/protocolbuffers/protobuf/commit/60e93d2d104f2af9cd345b1c6f3891d91430244a, https://github.com/protocolbuffers/protobuf/commit/c8e9b27d95c6ab2d0668b5889e7dac2c477b7038, https://github.com/protocolbuffers/protobuf

Severity

0

CVSS Score
0
10

Basic Information

Ecosystem
Base CVSS
0
EPSS Probability
0.00031%
EPSS Percentile
0.09395%
Introduced Version
0
Fix Available
4.33.6

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