Bug 2540113 (CVE-2026-88359)

Summary: CVE-2026-88359 libfyaml: libfyaml: Denial of Service via stack exhaustion
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in libfyaml. When processing a specially crafted YAML document, a remote attacker can trigger a stack exhaustion vulnerability in the `fy_atom_iter_format()` function. This occurs because the function repeatedly allocates memory on the stack without releasing it, leading to cumulative stack growth. This can cause the process to crash, resulting in a denial of service.
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Bug Depends On: 2540654    
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Description OSIDB Bzimport 2026-09-24 14:24:20 UTC 
libfyaml 0.9.6 contains a stack exhaustion vulnerability in fy_atom_iter_format(). When processing a specially crafted YAML document containing a very large literal or folded block scalar, the function repeatedly grows an internal buffer using alloca() inside a loop. The allocated stack memory is not released until the function returns, causing cumulative stack growth that can exceed the process stack limit and result in SIGSEGV and denial of service.