ALAS2-2025-3046

References: CVE-2025-61770  CVE-2025-61771  CVE-2025-61772 
FAQs regarding Amazon Linux ALAS/CVE Severity

Issue Overview:

Rack is a modular Ruby web server interface. In versions prior to 2.2.19, 3.1.17, and 3.2.2, `Rack::Multipart::Parser` buffers the entire multipart preamble (bytes before the first boundary) in memory without any size limit. A client can send a large preamble followed by a valid boundary, causing significant memory use and potential process termination due to out-of-memory (OOM) conditions. Remote attackers can trigger large transient memory spikes by including a long preamble in multipart/form-data requests. The impact scales with allowed request sizes and concurrency, potentially causing worker crashes or severe slowdown due to garbage collection. Versions 2.2.19, 3.1.17, and 3.2.2 enforce a preamble size limit (e.g., 16 KiB) or discard preamble data entirely. Workarounds include limiting total request body size at the proxy or web server level and monitoring memory and set per-process limits to prevent OOM conditions. (CVE-2025-61770)

Rack is a modular Ruby web server interface. In versions prior to 2.2.19, 3.1.17, and 3.2.2, ``Rack::Multipart::Parser` stores non-file form fields (parts without a `filename`) entirely in memory as Ruby `String` objects. A single large text field in a multipart/form-data request (hundreds of megabytes or more) can consume equivalent process memory, potentially leading to out-of-memory (OOM) conditions and denial of service (DoS). Attackers can send large non-file fields to trigger excessive memory usage. Impact scales with request size and concurrency, potentially leading to worker crashes or severe garbage-collection overhead. All Rack applications processing multipart form submissions are affected. Versions 2.2.19, 3.1.17, and 3.2.2 enforce a reasonable size cap for non-file fields (e.g., 2 MiB). Workarounds include restricting maximum request body size at the web-server or proxy layer (e.g., Nginx `client_max_body_size`) and validating and rejecting unusually large form fields at the application level. (CVE-2025-61771)

Rack is a modular Ruby web server interface. In versions prior to 2.2.19, 3.1.17, and 3.2.2, `Rack::Multipart::Parser` can accumulate unbounded data when a multipart part's header block never terminates with the required blank line (`CRLFCRLF`). The parser keeps appending incoming bytes to memory without a size cap, allowing a remote attacker to exhaust memory and cause a denial of service (DoS). Attackers can send incomplete multipart headers to trigger high memory use, leading to process termination (OOM) or severe slowdown. The effect scales with request size limits and concurrency. All applications handling multipart uploads may be affected. Versions 2.2.19, 3.1.17, and 3.2.2 cap per-part header size (e.g., 64 KiB). As a workaround, restrict maximum request sizes at the proxy or web server layer (e.g., Nginx `client_max_body_size`). (CVE-2025-61772)

Issue Correction:
Run yum update pcs or yum update --advisory ALAS2-2025-3046 to update your system.

New Packages:

aarch64:
    pcs-0.9.169-3.amzn2.3.0.7.aarch64
    pcs-snmp-0.9.169-3.amzn2.3.0.7.aarch64
    pcs-debuginfo-0.9.169-3.amzn2.3.0.7.aarch64

i686:
    pcs-0.9.169-3.amzn2.3.0.7.i686
    pcs-snmp-0.9.169-3.amzn2.3.0.7.i686
    pcs-debuginfo-0.9.169-3.amzn2.3.0.7.i686

src:
    pcs-0.9.169-3.amzn2.3.0.7.src

x86_64:
    pcs-0.9.169-3.amzn2.3.0.7.x86_64
    pcs-snmp-0.9.169-3.amzn2.3.0.7.x86_64
    pcs-debuginfo-0.9.169-3.amzn2.3.0.7.x86_64