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TI-2026-32018 Aliases CVE-2026-43973GHSA-r53j-fjj5-mv77

gun HTTP/1.1 response buffer has no size limit allowing server-controlled memory exhaustion

Priority MEDIUM 44CWE-770Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-770.

Summary

Uncontrolled Resource Consumption vulnerability in ninenines gun (gun_http module) allows a malicious server to exhaust client memory via unbounded HTTP/1.1 response buffering. In gun_http:handle/5, three clauses accumulate incoming TCP data into the connection's buffer field using binary concatenation with no upper-bound check: the head clause appends data until the \r\n\r\n header terminator is found; the body_chunked clause appends data whenever cow_http_te:stream_chunked/2 returns a more result indicating an incomplete chunk boundary; and the body_trailer clause appends data until the trailing \r\n\r\n is found. In each case, when the expected terminator never arrives, the enlarged binary is stored back into state and the process waits for more data, with no configurable or hard-coded ceiling on buffer size. A malicious or compromised server can exploit this by sending a partial response that never completes. For example, a response may begin with HTTP/1.1 200 OK\r\nX-Pad: followed by an unbounded stream of arbitrary bytes, never sending the header terminator. The gun connection process will continuously append the incoming data to its buffer, causing unbounded heap growth. Because BEAM imposes no per-process heap limit by default, a single malicious connection can exhaust all available memory on the node, causing a node-wide out-of-memory crash. This issue affects gun: from 1.0.0 before 2.4.0.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00482 41st percentileScored 2026-11-07
Fix Fixed gun (ninenines): 2.4.0gun (Hex): 2.4.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
nineninesgun1.0.0 to before 2.4.02.4.0Patch availableCNA
—gun (Hex)1.0.0 to before 2.4.02.4.0Patch availableGHSA-r53j-fjj5-mv77
  • gun Vendorninenines Affected 1.0.0 to before 2.4.0 Fixed in 2.4.0 Patch available CNA
  • gun (Hex) Vendor— Affected 1.0.0 to before 2.4.0 Fixed in 2.4.0 Patch available GHSA-r53j-fjj5-mv77

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:ninenines:gun:*:*:*:*:*:*:*:*1.0.0 to before 2.4.0Vulnerableninenines
  • cpe:2.3:a:ninenines:gun:*:*:*:*:*:*:*:* Versions 1.0.0 to before 2.4.0 Vulnerable ·ninenines

Remediation

  • Fix · CNA gun (ninenines) Fixed in 2.4.0
  • Fix · GHSA-r53j-fjj5-mv77 gun (Hex) Fixed in 2.4.0 Advisory →

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    ninenines gun 2.4.0

    3 records Highest priority Priority MEDIUM 2 MEDIUM, 1 LOW

    Other records, highest priority first

    • TI-2026-32019 gun HTTP/1.1 client accepts unsolicited 101 Switching Protocols response allowing server-driven protocol hijack and OOMPriority MEDIUM 44
    • TI-2026-32017 gun HTTP/2 PUSH_PROMISE authority not validated against connection origin allows cross-origin cookie injectionPriority LOW 27
    Show all 3 records →

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-43973
  2. 2026-10-03 Alias added: GHSA-r53j-fjj5-mv77
  3. 2026-10-21 EPSS moved to the 50th–90th percentile
  4. 2026-10-25 EPSS moved to the below the 50th percentile

References

Patch 2

Advisory 2

Other 1

  • TI-2026-32019 gun HTTP/1.1 client accepts unsolicited 101 Switching Protocols response allowing server-driven protocol hijack and OOM CVSS 4.0HIGH 8.7
  • TI-2026-32017 gun HTTP/2 PUSH_PROMISE authority not validated against connection origin allows cross-origin cookie injection CVSS 4.0MEDIUM 6.3

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences