CVE-2026-54425 Apache Software Foundation CVE debrief

Who should care

Defenders responsible for Apache bRPC deployments should assess exposure and prioritize upgrading to version 1.18.0 or applying the provided patch. They should also review and update affected systems to prevent potential denial-of-service attacks. This includes verifying and updating affected systems, reviewing compensating controls for exposed systems, and tracking exceptions and retesting remediated assets.

Why it matters

CVE-2026-54425 is a denial-of-service vulnerability in Apache bRPC that requires upgrading to version 1.18.0 or applying a patch to prevent potential attacks.

• Potential denial-of-service attacks via crafted HTTP/2 header blocks
• Need to verify and update affected systems to prevent potential attacks
• Priority on upgrading Apache bRPC to version 1.18.0 or applying the provided patch

Technical summary

Uncontrolled recursion in the HTTP/2 HPACK decoder in Apache bRPC before 1.18.0 allows remote attackers to cause denial of service by sending a crafted HTTP/2 header block containing many consecutive Dynamic Table Size Update entries. The decoder recursively decodes the next entry after processing a Dynamic Table Size Update without bounding the recursion depth. This can cause a stack exhaustion via recursive HPACK dynamic table size update decoding. Defenders should prioritize upgrading Apache bRPC to version 1.18.0 or applying the provided patch to prevent potential denial-of-service attacks.

Defensive priority

Defenders should prioritize upgrading Apache bRPC to version 1.18.0 or applying the provided patch to prevent potential denial-of-service attacks.

Recommended defensive actions

• Upgrade Apache bRPC to version 1.18.0
• Apply the provided patch to fix the issue
• Review and update affected systems to prevent potential denial-of-service attacks
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The CVE record and source item provide details on the vulnerability, including its cause, affected scenarios, and recommended fixes. The issue is caused by uncontrolled recursion in the HTTP/2 HPACK decoder in Apache bRPC before 1.18.0. The decoder recursively decodes the next entry after processing a Dynamic Table Size Update without bounding the recursion depth. A long sequence of update entries can consume excessive stack space, leading to a denial-of-service attack. Defenders should verify and update affected systems to prevent

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.