CVE-2026-78058 Vulnerability Analysis & Exploit Details

CVE-2026-78058
Vulnerability Scoring

Analysis In Progress
Analysis In Progress

Attack Complexity Details

  • Attack Complexity:
    Attack Complexity Analysis In Progress
  • Attack Vector:
    Attack Vector Under Analysis
  • Privileges Required: None
    No authentication is required for exploitation.
  • Scope:
    Impact is confined to the initially vulnerable component.
  • User Interaction: None
    No user interaction is necessary for exploitation.

CVE-2026-78058 Details

Status: Deferred

Last updated: 🕗 26 Oct 2026, 20:10 UTC
Originally published on: 🕛 21 Oct 2026, 12:17 UTC

Time between publication and last update: 5 days

CVSS Release:

CVE-2026-78058 Vulnerability Summary

CVE-2026-78058: Uncontrolled resource consumption in the HTTP/2 (h2) receive path of Apache bRPC (version < 1.18.0) on all platforms allows a remote unauthenticated attacker to crash the server or grow its memory without bound by sending crafted HTTP/2 frames. Root Cause: The h2 parser, enabled by default on every bRPC server port and used by h2/gRPC clients, trusts the peer to respect receive-side limits that bRPC advertises but never enforces: 1. SETTINGS_MAX_CONCURRENT_STREAMS defaulted to unlimited and was never checked on the server, letting a peer pin an unbounded number of pending streams per connection (~100x memory amplification). 2. SETTINGS_MAX_HEADER_LIST_SIZE defaulted to unlimited and was never enforced; 1-byte HPACK indexed references amplify a small HEADERS frame ~4000x into an unbounded decoded header list ("HPACK bomb"), and a never-completed HEADERS/CONTINUATION block accumulates memory without limit. 3. Control-frame acks (PING/SETTINGS acks, RST_STREAM, GOAWAY, WINDOW_UPDATE) unconditionally bypassed the -socket_max_unwritten_bytes write cap, so a PING flood combined with withheld TCP reads grew the connection buffer without the documented bound. 4. The HPACK dynamic table size update was validated against the protocol default (4096) instead of the advertised SETTINGS_HEADER_TABLE_SIZE, which together with the dynamic-table queue/accounting issue can desynchronize the decoder and dereference NULL (crash). Affected scenarios: Any bRPC server serving HTTP/h2/gRPC to an untrusted network, and any bRPC h2/gRPC client connecting to an untrusted backend. The h2 parser runs before any Authenticator check on the shared port. How to fix: Upgrade bRPC, or apply the patch in https://github.com/apache/brpc/pull/3474. Note: After applying the fix the following limits are enforced by default: - max_concurrent_streams: 1024 per connection (4294967295 restores unlimited). - max_header_list_size: 1 MiB decoded size per stream (4294967295 restores unlimited; -h2_client_max_header_list_size for clients). - h2 control-frame acks respect -socket_max_unwritten_bytes (-h2_ack_ignore_eovercrowded restores the old behavior). Requests exceeding these limits are rejected (RST_STREAM(REFUSED_STREAM) or a connection error).

Assessing the Risk of CVE-2026-78058

Access Complexity Graph

The exploitability of CVE-2026-78058 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2026-78058

No exploitability data is available for CVE-2026-78058.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2026-78058, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2026-78058, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2026-78058 does not compromise confidentiality.
  • Integrity: None
    CVE-2026-78058 does not impact data integrity.
  • Availability: None
    CVE-2026-78058 does not affect system availability.

CVE-2026-78058 References

External References

CWE Common Weakness Enumeration

CWE-476

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