Highly exploitable, CVE-2026-59803 poses a critical security risk that could lead to severe breaches.
Status: Deferred
Last updated: 🕡 10 Jul 2026, 18:46 UTC
Originally published on: 🕗 08 Jul 2026, 20:16 UTC
Time between publication and last update: 1 days
CVSS Release: version 3
disclosure@vulncheck.com
Secondary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVE-2026-59803: rpcx through 1.9.3, fixed in commit 047aec1, contains a denial-of-service vulnerability in protocol.Message.Decode (protocol/message.go). When a message has the compression flag set, the payload is gzip-decompressed via util.Unzip with no limit on the decompressed output size. The only built-in size guard, protocol.MaxMessageLength, is checked against the compressed on-the-wire frame length, not the decompressed size, so it provides no protection. Because decoding (and decompression) occurs in readRequest before authentication, a single unauthenticated connection can send a small (under 2 MB) gzip-compressed message that expands to gigabytes of heap allocation, leading to out-of-memory conditions and service unavailability.
The exploitability of CVE-2026-59803 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).
With low attack complexity and no required privileges, CVE-2026-59803 is an easy target for cybercriminals. Organizations should prioritize immediate mitigation measures to prevent unauthorized access and data breaches.
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.
Above is the CVSS Sub-score Breakdown for CVE-2026-59803, 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.
Below is the Impact Analysis for CVE-2026-59803, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.
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