CVE-2026-113431

HIGHCVSS 8.7/10

Last modified

CVE-2026-113431 is a high-severity vulnerability rated 8.7/10 on the CVSS scale. Allocation of Resources Without Limits or Throttling vulnerability in ninenines cowlib allows an unauthenticated remote peer to exhaust the memory of an HTTP/2 endpoint via HPACK-indexed header fields. cow_http2_machine:headers_decode/4 in src/cow_http2_machine.erl decodes every HEADERS block with cow_hpack:decode/3. It bounds the compressed block size and the number of fields, but not the size of the decoded header list that RFC 9113 section 6.5.2 places under SETTINGS_MAX_HEADER_LIST_SIZE.

Description

Allocation of Resources Without Limits or Throttling vulnerability in ninenines cowlib allows an unauthenticated remote peer to exhaust the memory of an HTTP/2 endpoint via HPACK-indexed header fields. cow_http2_machine:headers_decode/4 in src/cow_http2_machine.erl decodes every HEADERS block with cow_hpack:decode/3. It bounds the compressed block size and the number of fields, but not the size of the decoded header list that RFC 9113 section 6.5.2 places under SETTINGS_MAX_HEADER_LIST_SIZE. A peer stores one header value of up to the dynamic table size (4096 bytes by default) and then references it with one-byte indexed fields, so about 100 bytes on the wire decode to a header list of about 390 KB. A consumer that copies the decoded values, as Cowboy does when cowboy_http2:headers_to_map/2 joins repeated cookie fields into one binary, allocates that amount for every stream. The total across streams and connections is not bounded. This issue affects cowlib: from 2.7.0 onward.

Metrics

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
nineninescowlib>= 2.7.0, < *
nineninescowlib>= b461b119e78e4e09bb28b186b09da7ed4a86a0dd, < a3b15e29b3067644bfd580246c87f7af7a90b3b8

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-113431?
Allocation of Resources Without Limits or Throttling vulnerability in ninenines cowlib allows an unauthenticated remote peer to exhaust the memory of an HTTP/2 endpoint via HPACK-indexed header fields. cow_http2_machine:headers_decode/4 in src/cow_http2_machine.erl decodes every HEADERS block with cow_hpack:decode/3. It bounds the compressed block size and the number of fields, but not the size of the decoded header list that RFC 9113 section 6.5.2 places under SETTINGS_MAX_HEADER_LIST_SIZE. A peer stores one header value of up to the dynamic table size (4096 bytes by default) and then references it with one-byte indexed fields, so about 100 bytes on the wire decode to a header list of about 390 KB. A consumer that copies the decoded values, as Cowboy does when cowboy_http2:headers_to_map/2 joins repeated cookie fields into one binary, allocates that amount for every stream. The total across streams and connections is not bounded. This issue affects cowlib: from 2.7.0 onward.
How severe is CVE-2026-113431?
CVE-2026-113431 has a CVSS score of 8.7/10 (HIGH severity).
How do I fix CVE-2026-113431?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST