relibc CVE-2026-38641
HIGHAttack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessStage crafted malicious shared library
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DeliveryInduce target process to load it
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ExploitTrigger fault in DSO::mmap_and_copy
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ExecutionLoader mishandles mapped resources
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ImpactProcess crashes (denial of service)
Vulnerability Assessment
| Weakness |
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Resource release
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| Exploitation Conditions | Exploitation requires the victim process to load an attacker-controlled or crafted shared library through relibc's dynamic loader (the DSO::mmap_and_copy path); the attacker must therefore be able to supply or influence the .so file that is loaded. Limiting factors: the target must run on Redox OS / relibc (a research operating system with minimal production footprint), the malicious library must actually be loaded by a process, and impact is availability-only (process crash, no code execution or data exposure). Note the data conflict: the CVSS vector claims AV:N/PR:N (remote, unauthenticated) yet loading a crafted shared library implies local or operator-supplied input - verify the true reachability with the vendor before treating it as remotely exploitable. |
| Impact | Signals conflict on attack vector: the supplied CVSS 3.1 vector is AV:N/AC:L/PR:N/UI:N/A:H (7.5), but the described trigger - getting a process to load a crafted shared library - is inherently a local/operator-controlled action, so AV:N likely overstates remote reachability; verify with the vendor. EPSS is low (0.17%, 6th percentile) and the issue is absent from CISA KEV, consistent with no mass exploitation despite publicly available POC code. SSVC data is not provided, but technical impact is availability-only with no scope change, and exploitation is not automatable in any obvious network-facing way. Net: a legitimate availability bug worth fixing in Redox/relibc deployments, but a low real-world priority given the niche platform, availability-only impact, and likely local trigger - the headline 7.5 reflects the A:H plus AV:N assumption more than realistic widespread risk. |
| Exploit ScenarioDerived | An attacker crafts a malformed ELF shared object and arranges for a relibc-based process on Redox OS to load it - for example by placing it on a library search path or passing it to a program that dlopen()s untrusted paths. When the dynamic loader reaches DSO::mmap_and_copy, the malformed segment data triggers the resource-handling fault and crashes the process, denying service. Public POC code for this exact CVE is available at https://github.com/Marsman1996/pocs/tree/master/redox/CVE-2026-38641. |
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Alert meAnalysisAIv1 – Jun 29, 2026
Denial of service in relibc (the Redox OS C standard library) at commit 61f42d allows attackers to crash a process by getting it to load a maliciously crafted shared library, which mishandles resources in the DSO::mmap_and_copy dynamic-linking routine (CWE-404). Publicly available exploit code exists, but the flaw is not in CISA KEV and EPSS is very low (0.17%, 6th percentile), indicating no observed in-the-wild exploitation. Impact is confined to availability - no confidentiality or integrity loss.
RemediationAI
Upstream fix available (PR/commit); released patched version not independently confirmed - apply the change from the Redox relibc merge request at https://gitlab.redox-os.org/redox-os/relibc/-/merge_requests/1046 (tracking issue https://gitlab.redox-os.org/redox-os/relibc/-/issues/263) by rebuilding relibc past the fixing commit, since no tagged patched release version is provided in the data. As a compensating control until rebuilt, restrict which shared libraries the system will load: only load .so files from trusted, write-protected paths and tighten directory/file permissions on library search paths to prevent attacker-supplied objects, accepting the trade-off that custom or third-party libraries placed outside trusted paths will no longer load. Avoid loading untrusted or user-supplied shared libraries (e.g. via dlopen of attacker-controlled paths), and validate ELF inputs before loading where feasible.
Affects your stack
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Technical ContextAI · show details
relibc is Redox OS's from-scratch C standard library written largely in Rust, providing libc/dynamic-loader functionality including ELF shared-object (DSO) loading. The vulnerable DSO::mmap_and_copy function is part of the dynamic linker that memory-maps and copies a shared library's segments into memory at load time. CWE-404 (Improper Resource Shutdown or Release) points to mishandling of mapped memory or descriptors when parsing a malformed ELF, which can be triggered by a crafted .so to abort or crash the loading process. The CPE in the feed is a placeholder ('cpe:2.3:a:n/a:n/a'), so the affected component is identified only from the description and Redox upstream tracker, not from structured CPE data.
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Triggering requires supplying a crafted library to a loading process, implying local, low-privilege access (AV:L/PR:L); impact is availability-only crash, so C:N/I:N/A:H.
Primary rating from Vendor (mitre).
CVSS VectorVendor: mitre
Lifecycle Timeline
2DescriptionCVE.org
An issue in the DSO::mmap_and_copy function of relibc commit 61f42d allows attackers to cause a Denial of Service (DoS) via loading a crafted shared library.
Executive ViewAI
A denial-of-service vulnerability in relibc (Redox OS's C standard library) allows attackers to crash processes by loading maliciously crafted shared libraries. While publicly available exploit code exists, no evidence of active exploitation has been observed (EPSS 0.2%), and the vulnerability affects only the niche Redox OS platform; organizations should prioritize based on whether production infrastructure depends on Redox OS.
No vendor-released patch identified at time of analysis. Interim mitigations include restricting dynamic shared object (DSO) loading to trusted sources only, implementing process-level isolation and restart automation to recover from crashes, validating shared library integrity and signature verification before loading, and limiting process privileges to reduce blast radius of compromised services.
Threat Intelligence Overview
NVD
CVE.org
EPSS
Vulnrichment
GitHub
VulDB
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.
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