Bug 2554173 (CVE-2026-102941)

Summary: CVE-2026-102941 github.com/gomarkdown/markdown: github.com/gomarkdown/markdown: Denial of Service via short URL parsing
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, blitton, dpaolell, gparvin, jbalunas, jdelft, jupierce, lgarciaa, mbarnett, mbiarnes, ppalepu, ppostler, prdhamdh, rhaigner, sghai, sidsharm, suppawar, tsze, vlaad
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in github.com/gomarkdown/markdown. A remote attacker can cause a Denial of Service (DoS) by submitting specially crafted Markdown content containing empty or very short link destinations. When link sanitization is enabled, the parser attempts to read beyond the boundaries of the input string without verifying its length. This issue triggers an unhandled crash, terminating the running process.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2555410, 2555411, 2555412, 2555416, 2555417    
Bug Blocks:    

Description OSIDB Bzimport 2026-10-16 15:57:13 UTC 
The package github.com/gomarkdown/markdown is a Go library for parsing Markdown text and rendering as HTML. Prior to 0.0.0-20260724235538-61af6e1e6971, parser.IsSafeURL in parser/parser.go slices url[:nPath] before the len(url) >= nPath guard. A short destination causes a slice-bounds panic when the loop reaches a relative-path prefix for which len(url) < nPath and cap(url) < nPath. The one-byte destination / is an explicit non-panic counterexample because it matches the first valid path and returns before a longer prefix is sliced. Demonstrated panic cases include empty, ., and .. destinations under those conditions. The panic is reachable when markdown.ToHTML renders untrusted Markdown with html.Safelink enabled, including an empty link destination, and is also reachable by callers that pass a short attacker-controlled URL directly to the exported parser.IsSafeURL function. An uncaught panic can terminate the calling process and cause denial of service. This issue is fixed in 0.0.0-20260724235538-61af6e1e6971.