CVE-2021-41099 | Integer overflow issue with strings in Redis

Redis is an open source, in-memory database that persists on disk. An integer overflow bug in the underlying string library can be used to corrupt the heap and potentially result with denial of service or remote code execution. The vulnerability involves changing the default proto-max-bulk-len configuration parameter to a very large value and constructing specially crafted network payloads or commands. The problem is fixed in Redis versions 6.2.6, 6.0.16 and 5.0.14. An additional workaround to mitigate the problem without patching the redis-server executable is to prevent users from modifying the proto-max-bulk-len configuration parameter. This can be done using ACL to restrict unprivileged users from using the CONFIG SET command.

Published: 2021-10-04 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-41099 is rated Moderate Risk (63.6/100): CVSS High severity, with medium exploitation likelihood (EPSS 3.42%). EPSS rose +3.02% over the last day, indicating growing attacker interest. 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-2021-41099

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 2026-06-15 0.40% 3.42% +3.02%
2 2026-04-19 0.30% 0.40% +0.11%
3 2026-04-04 — 0.30% —

Full EPSS history (24 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-41099

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]
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]
6.0 2.0 MEDIUM
AV:N/AC:M/Au:S/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 6.8 6.4 [email protected]

Weakness enumeration for CVE-2021-41099

OS Trackers for CVE-2021-41099

vendor priority summary link
alpine high CVE-2021-41099: 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-2021-41099
debian not yet assigned CVE-2021-41099 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-2021-41099
gentoo high CVE-2021-41099: 1 GLSA(s) (202209-17), 1 atom(s) (dev-db/redis); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-41099
redhat high — https://access.redhat.com/security/cve/CVE-2021-41099
suse high CVE-2021-41099 severity important: SUSE including 7 source package names (redis, redis-6.0.14-6.8.1, …), 9 product×package rows across 6 product lines (SUSE Liberty Linux 8, SUSE Linux Enterprise Module for Server Applications 15 SP2, … (6 product lines)): Fixed 8, Known Not Affected 1. https://www.suse.com/security/cve/CVE-2021-41099/
ubuntu medium CVE-2021-41099 medium priority: Ubuntu including 1 source packages (redis), 14 status rows across 14 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, trusty, upstream, xenial): not-affected 9, released 3, ignored 2. https://ubuntu.com/security/CVE-2021-41099

Affected software / configurations for CVE-2021-41099

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:*:*:*:*:*:*:*:*
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:*:*:*:*:*:*:*
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:*:*:*:*:*:*:*
netapp management_services_for_element_software_and_netapp_hci — cpe:2.3:a:netapp:management_services_for_element_software_and_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-2021-41099

URL Tags
https://github.com/redis/redis/commit/c6ad876774f3cc11e32681ea02a2eead00f2c521 Patch Third Party Advisory
https://github.com/redis/redis/security/advisories/GHSA-j3cr-9h5g-6cph 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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