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Fencer Vulns
high 8.8

CVE-2021-32765 json

Integer Overflow to Buffer Overflow in Hiredis

published 2021-10-04 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-19533

cvss
8.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.1%
EPSS 2.1% chance of exploitation in 30 days, percentile 81%
public exploits
0
none known

Summary

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.

Patch / fix

  • redis hiredis 1.0.1
  • hiredis Debian 14, Debian 13, Debian 12 0.14.1-2

debian advisories DEBIAN-CVE-2021-32765

  • hiredis openSUSE Tumbleweed 1.0.2-1.1
  • hiredis Package Hub 15 SP2 0.13.3-bp152.4.3.1
  • hiredis Package Hub 15 SP3, openSUSE Leap 15.3, openSUSE Leap 15.2 0.13.3-bp153.2.3.1

opensuse advisories openSUSE-SU-2024:11561-1openSUSE-SU-2021:1550-1openSUSE-SU-2021:1536-1

  • hiredis Arch Linux 1.0.1-1

arch linux advisories AVG-2441

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-32765 updated cvss 8.8

hiredis: an integer overflow may occur if provided maliciously crafted or corrupted RESP mult-bulk protocol data

  • Red Hat Ansible Automation Platform 1.2 hiredis Red Hat Ansible Tower 3 hiredis
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.05% chance of exploitation in the next 30 days, higher than 81% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 6.5 AV:N/AC:L/Au:S/C:P/I:P/A:P

Affected products

  • redis hiredis

Classification

Weakness
  • CWE-190 Integer Overflow or Wraparound
  • CWE-680 Integer Overflow to Buffer Overflow

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.