CVE-2026-43970
HighSummary
CVE-2026-43970 is a vulnerability related to improper handling of highly compressed data in the cowlib library, which can lead to remote denial of service attacks via memory exhaustion. It allows unauthenticated users to send specially crafted SPDY frames that can cause significant memory consumption.
Risk Assessment
Organizations using cowlib may be exposed to attacks that lead to service outages due to memory exhaustion, resulting in downtime and loss of application availability.
Recommendation
It is recommended to update the cowlib library to version 2.16.1 or later to mitigate this vulnerability. Additionally, implementing input size restrictions can help minimize the risk.
Other vulnerabilities in cowlib
See all- CVE-2026-43971Medium
Improper Encoding or Escaping of Output vulnerability in ninenines cowlib allows Link header directive smuggling via unescaped special characters in cow_link:link/1. cow_link:do_link/1 in cowlib interpolates the target URI, rel value, and attribute keys directly into the serialized Link: header value without escaping or token-grammar validation. A > byte in target prematurely closes the URI slot, allowing an attacker to append additional link entries with attacker-chosen rel directives. A " or \ in rel escapes the quoted string and opens new parameters. Any byte — including whitespace, =, and " — in an attribute key is emitted verbatim. Because browsers act on Link: directives such as rel="preconnect", rel="preload", and rel="prerender", an attacker who can influence these fields in an application that round-trips parsed Link headers through cow_link:link/1 can force victim browsers to make out-of-band connections to attacker-controlled origins. This issue affects cowlib: from 2.9.0 onward.
- CVE-2026-59248High
A vulnerability in the cowlib library allows an unauthenticated remote attacker to exhaust memory on a vulnerable server or client by sending specially crafted HTTP/2 or HTTP/3 frames. The issue stems from missing limits in the HPACK and QPACK decoder, which processes arbitrarily long prefixed integers, causing large bignum allocations and heavy garbage collection churn.
- CVE-2026-43966Medium
A CRLF injection vulnerability in cowlib version 2.9.0 allows HTTP response splitting due to improper neutralization of non-VCHAR bytes in structured HTTP header values. The escape_string/2 function fails to escape CR and LF characters, enabling attackers to inject new headers into HTTP responses.
- CVE-2026-43969Low
CRLF Injection vulnerability in cowlib allows HTTP request splitting and cookie smuggling via unvalidated cookie name and value fields. The cow_cookie:cookie/1 function builds a Cookie header without validation, allowing an attacker to inject ;, ,, CR, LF, or TAB characters.
Original NVD description (English source)
Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in ninenines cowlib allows unauthenticated remote denial of service via memory exhaustion. cow_spdy:inflate/2 in cowlib passes peer-supplied compressed bytes directly to zlib:inflate/2 with no output size bound. The SPDY header compression dictionary (?ZDICT) is public, and zlib compresses long runs of repeated bytes at roughly 1024:1, so a few kilobytes of SPDY frame payload can decompress to gigabytes on the BEAM heap, OOM-killing the node. A single unauthenticated SPDY frame is sufficient to trigger the condition. The parsers for syn_stream, syn_reply, and headers frame types are all affected via cow_spdy:parse_headers/2. This issue affects cowlib from 0.1.0 before 2.16.1.