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.
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Thu, 16 Apr 2026 19:15:00 +0000
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| Description | 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. | |
| Title | zlib: Buffer Overflow in Zlib::GzipReader ungetc via large input leads to memory corruption | |
| Weaknesses | CWE-120 CWE-131 |
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cvssV4_0
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Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-04-16T18:20:21.451Z
Reserved: 2026-02-24T02:32:39.799Z
Link: CVE-2026-27820
Updated: 2026-04-16T18:20:15.404Z
Status : Received
Published: 2026-04-16T18:16:44.770
Modified: 2026-04-16T18:16:44.770
Link: CVE-2026-27820
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OpenCVE Enrichment
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