CVE detail
CVE-2026-27820
zlib is a Ruby interface for the zlib compression/decompression library. Versions 3.0.0 and below, 3.1.0, 3.1.1, 3.2.0 and 3.2.1 contain a buffer overflow vulnerability in the Zlib::GzipReader. The zstream_buffer_ungets function prepends caller-provided bytes ahead of previously produced output but fails to guarantee the backing Ruby string has enough capacity before the memmove shifts the existing data. This can lead to memory corruption when the buffer length exceeds capacity. This issue has been fixed in versions 3.0.1, 3.1.2 and 3.2.3.
Buzz score
Why this CVE is surfacing
This all-time snapshot uses the same composite formula as Trending across a 30-year evidence window, rather than a current rolling window.
Buzz score components · mention 13.9 · diversity 11.5 · KEV 0.0 · OTX 0.0 · PoC 0.0
Why it matters now
Mention timeline
- Total mentions
- 0
- within the 30d window
- Peak daily
- 0
- highest bucket
Evidence
Source links by recency
3 source links · newest first
- CVE-2026-27820 zlib: Buffer Overflow in Zlib::GzipReader ungetc via large input leads to memory corruptionMicrosoft MSRC
Information published.
vendormsrc.microsoft.comApr 23, 2026, 8:11 AM - https://hackerone.com/reports/3467067hackerone.com
No excerpt available.
Exploithackerone.comApr 16, 2026, 6:16 PM No excerpt available.
Exploitgithub.comApr 16, 2026, 6:16 PM
Exploit code
Public exploit repository references
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0 repository references · best confidence N/A · max 0 stars
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