Client crash and heap disclosure via glyph replay
Published Aug 19, 2026 · Updated Aug 25, 2026
Out-of-bounds read in FreeRDP before 3.27.0 allows remote attackers controlling an RDP server to crash clients or disclose heap data. glyph_cache_get accepts an index equal to the cache size, so GLYPH_FRAGMENT_USE replay reads one pointer beyond the entries array and dereferences it as a glyph. Exploitation requires a client connection to the malicious server; the default glyph cache is exposed, while disclosure depends on adjacent heap layout.
Summary
What happened
Out-of-bounds read in FreeRDP before 3.27.0 allows remote attackers controlling an RDP server to crash clients or disclose heap data. glyph_cache_get accepts an index equal to the cache size, so GLYPH_FRAGMENT_USE replay reads one pointer beyond the entries array and dereferences it as a glyph. Exploitation requires a client connection to the malicious server; the default glyph cache is exposed, while disclosure depends on adjacent heap layout.
The record
- CVE
- CVE-2026-55564
- Published
- Aug 19, 2026
- Updated
- Aug 25, 2026
- Vendor
- FreeRDP
- Product
- FreeRDP
- Classifications
- CWE-125, CWE-193, T1499
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 19, 2026CVE publishedPublication date reported by the CVE source.
- Aug 25, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 3.27.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Glyph-fragment handler proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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