CVE-2021-32762 | Integer overflow that can lead to heap overflow in redis-cli, redis-sentinel on some platforms

Redis is an open source, in-memory database that persists on disk. The redis-cli command line tool and redis-sentinel service may be vulnerable to integer overflow when parsing specially crafted large multi-bulk network replies. This is a result of a vulnerability in the underlying hiredis library which does not perform an overflow check before calling the calloc() heap allocation function. This issue only impacts systems with heap allocators that do not perform their own overflow checks. Most modern systems do and are therefore not likely to be affected. Furthermore, by default redis-sentinel uses the jemalloc allocator which is also not vulnerable. The problem is fixed in Redis versions 6.2.6, 6.0.16 and 5.0.14.

Published: 2021-10-04 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-32762 is rated Moderate Risk (56.6/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.87%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-32762

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-16 0.70% 0.87% +0.17%
2 2026-04-04 0.87% 0.70% -0.17%
3 2026-01-08 — 0.87% —

Full EPSS history (29 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-32762

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.6 5.9 [email protected]
8.8 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 5.9 [email protected]
9.0 2.0 HIGH
AV:N/AC:L/Au:S/C:C/I:C/A:C Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:C)
Complete confidentiality impact.
Integrity impact (I:C)
Complete integrity impact.
Availability impact (A:C)
Complete availability impact.
 8.0 10.0 [email protected]

Weakness enumeration for CVE-2021-32762

OS Trackers for CVE-2021-32762

vendor priority summary link
alpine high CVE-2021-32762: 1 source package rows (redis); 34 state rows across 10 repos (3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-community, 3.21-community, 3.22-community, edge-community, edge-main); fixed 10, open 24. https://security.alpinelinux.org/vuln/CVE-2021-32762
debian not yet assigned CVE-2021-32762 not yet assigned priority: Debian including 1 source packages (redis), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-32762
gentoo high CVE-2021-32762: 1 GLSA(s) (202209-17), 1 atom(s) (dev-db/redis); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-32762
redhat medium — https://access.redhat.com/security/cve/CVE-2021-32762
suse high CVE-2021-32762 severity important: SUSE including 4 source package names (redis, redis-6.0.14-6.8.1, redis-6.2.6-1.1, redis-6.2.6-150400.1.5), 6 product×package rows across 5 product lines (SUSE Linux Enterprise Module for Server Applications 15 SP2, SUSE Linux Enterprise Module for Server Applications 15 SP3, … (5 product lines)): Fixed 5, Known Not Affected 1. https://www.suse.com/security/cve/CVE-2021-32762/
ubuntu negligible CVE-2021-32762 negligible priority: Ubuntu including 7 source packages (discque, hiredis, …), 105 status rows across 15 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 82, DNE 18, ignored 2, needed 1, needs-triage 1, released 1. https://ubuntu.com/security/CVE-2021-32762

Affected software / configurations for CVE-2021-32762

Vendor Product Version Raw CPE
redis redis >= 5.0.0, < 5.0.14 cpe:2.3:a:redis:redis:*:*:*:*:*:*:*:*
redis redis >= 6.0.0, < 6.0.16 cpe:2.3:a:redis:redis:*:*:*:*:*:*:*:*
redis redis >= 6.2.0, < 6.2.6 cpe:2.3:a:redis:redis:*:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
debian debian_linux 11.0 cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
fedoraproject fedora 34 cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
fedoraproject fedora 35 cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*
netapp management_services_for_element_software — cpe:2.3:a:netapp:management_services_for_element_software:-:*:*:*:*:*:*:*
netapp management_services_for_netapp_hci — cpe:2.3:a:netapp:management_services_for_netapp_hci:-:*:*:*:*:*:*:*
oracle communications_operations_monitor 4.3 cpe:2.3:a:oracle:communications_operations_monitor:4.3:*:*:*:*:*:*:*
oracle communications_operations_monitor 4.4 cpe:2.3:a:oracle:communications_operations_monitor:4.4:*:*:*:*:*:*:*
oracle communications_operations_monitor 5.0 cpe:2.3:a:oracle:communications_operations_monitor:5.0:*:*:*:*:*:*:*

References for CVE-2021-32762

URL Tags
https://github.com/redis/redis/commit/0215324a66af949be39b34be2d55143232c1cb71 Patch Third Party Advisory
https://github.com/redis/redis/security/advisories/GHSA-833w-8v3m-8wwr Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HTYQ5ZF37HNGTZWVNJD3VXP7I6MEEF42/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VL5KXFN3ATM7IIM7Q4O4PWTSRGZ5744Z/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WR5WKJWXD4D6S3DJCZ56V74ESLTDQRAB/
https://security.gentoo.org/glsa/202209-17 Third Party Advisory
https://security.netapp.com/advisory/ntap-20211104-0003/ Third Party Advisory
https://www.debian.org/security/2021/dsa-5001 Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.html Patch Third Party Advisory
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