CVE-2026-78058 Apache Software Foundation CVE debrief

Who should care

Defenders responsible for Apache bRPC servers, especially those with publicly accessible ports, should assess exposure and prioritize remediation. This includes administrators, security teams, and developers using Apache bRPC.

Why it matters

Defenders should care about CVE-2026-78058 because it allows remote unauthenticated attackers to crash Apache bRPC servers or grow their memory without bound, potentially leading to denial-of-service attacks. The vulnerability affects Apache bRPC versions less than 1.18.0 and requires verification of exposure and remediation priority.

• Potential for server crashes and memory amplification attacks
• Possible growth of server memory without bounds
• Need for verification of exposure and remediation priority

Technical summary

The vulnerability exists in the HTTP/2 (h2) receive path of Apache bRPC versions less than 1.18.0. A remote unauthenticated attacker can send crafted HTTP/2 frames to crash the server or grow its memory without bound. The root cause is the h2 parser's trust in the peer to respect receive-side limits that bRPC advertises but never enforces. This includes unlimited default settings for SETTINGS_MAX_CONCURRENT_STREAMS and SETTINGS_MAX_HEADER_LIST_SIZE, which can lead to memory amplification attacks. Control-frame acks also bypass the socket_max_unwritten_bytes write cap, allowing for a PING flood combined with withheld TCP reads to grow the connection buffer without bounds.

Defensive priority

Defenders should prioritize verifying exposure of Apache bRPC servers, especially those with publicly accessible ports, and assess the potential for memory amplification attacks. Remediation involves upgrading to version 1.18.0 or later.

Recommended defensive actions

• Verify Apache bRPC server exposure and assess potential for memory amplification attacks
• Upgrade to version 1.18.0 or later
• Monitor server memory usage and crash reports for signs of exploitation
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the vulnerability, including its root cause, affected versions, and potential impacts. However, specific details on exploitation and victim impact are limited.

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.