# CVE-2021-32765

## Summary

- **CVE ID:** CVE-2021-32765
- **Severity:** HIGH
- **CVSS Score:** 8.8 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** CWE-190, CWE-680
- **Published:** Oct 4, 2021
- **Last Modified:** Mar 13, 2026

## Description

Hiredis is a minimalistic C client library for the Redis database. In affected versions Hiredis is vulnurable to integer overflow if provided maliciously crafted or corrupted `RESP` `mult-bulk` protocol data. When parsing `multi-bulk` (array-like) replies, hiredis fails to check if `count * sizeof(redisReply*)` can be represented in `SIZE_MAX`. If it can not, and the `calloc()` call doesn't itself make this check, it would result in a short allocation and subsequent buffer overflow. Users of hiredis who are unable to update may set the [maxelements](https://github.com/redis/hiredis#reader-max-array-elements) context option to a value small enough that no overflow is possible.

## Affected Products

- redis — hiredis (< 1.0.1)

## References

- [CNA](https://github.com/redis/hiredis/security/advisories/GHSA-hfm9-39pp-55p2)
- [CNA](https://github.com/redis/hiredis/commit/76a7b10005c70babee357a7d0f2becf28ec7ed1e)
- [CNA](https://wiki.sei.cmu.edu/confluence/display/c/MEM07-C.+Ensure+that+the+arguments+to+calloc%28%29%2C+when+multiplied%2C+do+not+wrap)
- [CNA](https://lists.debian.org/debian-lts-announce/2021/10/msg00007.html)
- [CNA](https://security.netapp.com/advisory/ntap-20211104-0003/)
- [CNA](https://security.gentoo.org/glsa/202210-32)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.51%
- **EPSS Percentile:** 65.8

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._