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Fencer Vulns
high 7.5

CVE-2025-21605 json

Redis DoS Vulnerability due to unlimited growth of output buffers abused by unauthenticated client

published 2025-04-23 18 mo ago modified 2026-09-08 2 mo ago also BIT-keydb-2025-21605 , BIT-redis-2025-21605 , BIT-valkey-2025-21605 , EUVD-2025-12407 , GHSA-r67f-p999-2gff

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 59%
public exploits
0
none known

Summary

Redis is an open source, in-memory database that persists on disk. In versions starting at 2.6 and prior to 7.4.3, An unauthenticated client can cause unlimited growth of output buffers, until the server runs out of memory or is killed. By default, the Redis configuration does not limit the output buffer of normal clients (see client-output-buffer-limit). Therefore, the output buffer can grow unlimitedly over time. As a result, the service is exhausted and the memory is unavailable. When password authentication is enabled on the Redis server, but no password is provided, the client can still cause the output buffer to grow from "NOAUTH" responses until the system will run out of memory. This issue has been patched in version 7.4.3. An additional workaround to mitigate this problem without patching the redis-server executable is to block access to prevent unauthenticated users from connecting to Redis. This can be done in different ways. Either using network access control tools like firewalls, iptables, security groups, etc, or enabling TLS and requiring users to authenticate using client side certificates.

Patch / fix

  • bitnami keydb 6.2.18, 7.2.8, 7.4.3
  • bitnami redis 6.2.18, 7.2.8, 7.4.3
  • bitnami valkey 7.2.9, 8.0.3, 8.1.1
  • redis redis 6.2.18, 7.2.8, 7.4.3
  • redislabs redis 6.2.18, 7.2.8, 7.4.3
  • lfprojects valkey 7.2.9, 8.0.3, 8.1.1
  • linuxfoundation valkey 7.2.9, 8.0.3, 8.1.1
  • valkey-io valkey 7.2.9, 8.0.3, 8.1.1
  • redict redict 7.3.3
  • redis Debian 12 5:7.0.15-1~deb12u4
  • redis Debian 14, Debian 13 5:7.0.15-3.1
  • redict Debian 14 7.3.5+ds-1
  • valkey Debian 14, Debian 13 8.1.1+dfsg1-1

debian advisories DEBIAN-CVE-2025-21605

  • valkey Ubuntu 24.04 LTS 7.2.11+dfsg1-0ubuntu0.2

ubuntu advisories UBUNTU-CVE-2025-21605

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • redis RHEL 8 6.2.18-1.module+el8.10.0+23050+05ea4e95
  • discovery-cli discovery 1.0 1.14.0-1.el8
  • discovery-cli discovery 1.0 1.14.0-1.el9
  • discovery-installer discovery 1.0 1.14.1-1.el8
  • discovery-installer discovery 1.0 1.14.1-1.el9
  • valkey RHEL 10.0 8.0.3-1.el10_0
  • redis RHEL 9 6.2.18-1.el9_6
  • redis RHEL 9 7.2.8-1.module+el9.6.0+23049+8374f320

red hat advisories RHSA-2025:7686RHSA-2025:7630RHSA-2025:7538RHSA-2025:7509RHSA-2025:7438RHSA-2025:7429

  • redis SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS +1 more 6.0.14-150200.6.35.1
  • valkey SLE Module for Server Applications 15 SP7 8.0.2-150700.3.5.1
  • valkey SLE Module for Server Applications 15 SP6, openSUSE Leap 15.6 8.0.2-150600.13.6.1
  • redis SLE Module for Server Applications 15 SP6, openSUSE Leap 15.6 7.2.4-150600.3.9.1
  • redis7 SLE Module for Server Applications 15 SP6, openSUSE Leap 15.6 7.0.8-150600.8.9.1
  • redis SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +7 more 6.2.6-150400.3.34.1
  • redis7 SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE High Performance Computing 15 SP5-LTSS +1 more 7.0.8-150500.3.18.1

suse advisories SUSE-SU-2025:02010-1SUSE-SU-2025:01942-1SUSE-SU-2025:1566-1SUSE-SU-2025:1433-1SUSE-SU-2025:1432-1SUSE-SU-2025:1420-1

  • redis openSUSE Tumbleweed 8.0.2-1.1
  • valkey openSUSE Tumbleweed 8.0.3-1.1

opensuse advisories openSUSE-SU-2025:15293-1openSUSE-SU-2025:15035-1

  • redis AlmaLinux 8 6.2.18-1.module_el8.10.0+3994+c2cc5395
  • redis AlmaLinux 9 7.2.8-1.module_el9.6.0+168+b8d8e900
  • redis AlmaLinux 9 6.2.18-1.el9_6
  • valkey AlmaLinux 10 8.0.3-1.el10_0

almalinux advisories ALSA-2025:7686ALSA-2025:7429ALSA-2025:7438ALSA-2025:7509

  • redis Rocky Linux 9 7.2.8-1.module+el9.6.0+32036+eb8f79e6
  • redis Rocky Linux 9 6.2.18-1.el9_6
  • valkey Rocky Linux 10 8.0.3-1.el10_0
  • redis Rocky Linux 8 6.2.18-1.module+el8.10.0+1980+8f0924a4

rocky linux advisories RLSA-2025:7429RLSA-2025:7438RLSA-2025:7509RLSA-2025:7686

  • redis Alpine 3.15 6.2.18-r0
  • redis Alpine 3.18 7.0.15-r3
  • redis Alpine 3.21, Alpine 3.20, Alpine 3.19 7.2.8-r0
  • redis Alpine 3.24, Alpine 3.23, Alpine 3.22 8.0.0-r0
  • redict Alpine 3.24, Alpine 3.23, Alpine 3.22 +2 more 7.3.3-r0
  • valkey Alpine 3.24, Alpine 3.23, Alpine 3.22 +2 more 7.2.9-r0

alpine advisories ALPINE-CVE-2025-21605

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • valkey Azure Linux 3.0 8.0.3-1

azure linux advisories AZL-60939

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

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-2025-21605 updated cvss 7.5

redis: Redis DoS Vulnerability due to unlimited growth of output buffers abused by unauthenticated client

  • Red Hat OpenShift Lightspeed openshift-lightspeed-tech-preview/lightspeed-service-api-rhel9
    affected: workaround, no fix available
  • Red Hat Discovery 1 for RHEL 8 discovery-cli 1.14.0-1.el8, discovery-installer 1.14.1-1.el8 Red Hat Discovery 1 for RHEL 9 discovery-cli 1.14.0-1.el9, discovery-installer 1.14.1-1.el9
    fixed: vendor fix RHSA-2025:7630
  • Red Hat Quay v3 quay/quay-rhel8 v3.13.6-5, quay/quay-rhel8 v3.14.2-7, quay/quay-rhel8 v3.9.12-7, quay/clair-rhel8 v3.13.6-1, quay/clair-rhel8 v3.14.2-1, quay/clair-rhel8 v3.9.12-2, +54 more
    fixed: vendor fix RHBA-2025:8687
  • Red Hat Enterprise Linux AppStream (v. 8) redis 6.2.18-1.module+el8.10.0+23050+05ea4e95
    fixed: vendor fix RHSA-2025:7686
  • Red Hat Enterprise Linux AppStream (v. 9) redis 6.2.18-1.el9_6, redis 7.2.8-1.module+el9.6.0+23049+8374f320
    fixed: vendor fix RHSA-2025:7438
  • Red Hat Enterprise Linux AppStream (v. 10) valkey 8.0.3-1.el10_0
    fixed: vendor fix RHSA-2025:7509
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) redis 6.0.9-5.module+el8.4.0+23067+0d16e377.2
    fixed: vendor fix RHSA-2025:4441
  • Red Hat Enterprise Linux AppStream AUS (v.8.6) redis 6.0.9-5.module+el8.6.0+23072+c1b08039.2
    fixed: vendor fix RHSA-2025:4561
show 11 more
  • Red Hat Enterprise Linux AppStream E4S (v.8.4) redis 6.0.9-5.module+el8.4.0+23067+0d16e377.2
    fixed: vendor fix RHSA-2025:4441
  • Red Hat Enterprise Linux AppStream E4S (v.8.6) redis 6.0.9-5.module+el8.6.0+23072+c1b08039.2
    fixed: vendor fix RHSA-2025:4561
  • Red Hat Enterprise Linux AppStream E4S (v.9.0) redis 6.2.6-1.el9_0.2
    fixed: vendor fix RHSA-2025:4577
  • Red Hat Enterprise Linux AppStream EUS (v.8.8) redis 6.2.7-1.module+el8.8.0+23086+95b1dcd4.3
    fixed: vendor fix RHSA-2025:4607
  • Red Hat Enterprise Linux AppStream EUS (v.9.2) redis 6.2.7-1.el9_2.2
    fixed: vendor fix RHSA-2025:4789
  • Red Hat Enterprise Linux AppStream EUS (v.9.4) redis 6.2.7-1.el9_4.2, redis 7.0.12-1.module+el9.4.0+23090+d27b104d.3
    fixed: vendor fix RHSA-2025:4788
  • Red Hat Enterprise Linux AppStream TUS (v.8.4) redis 6.0.9-5.module+el8.4.0+23067+0d16e377.2
    fixed: vendor fix RHSA-2025:4441
  • Red Hat Enterprise Linux AppStream TUS (v.8.6) redis 6.0.9-5.module+el8.6.0+23072+c1b08039.2
    fixed: vendor fix RHSA-2025:4561
  • Red Hat Developer Hub 1 rhdh/rhdh-hub-rhel9
    not affected: component not present
  • Red Hat Enterprise Linux 9 valkey
    not affected: vulnerable code not present
  • Red Hat Enterprise Linux AI (RHEL AI) rhelai1/bootc-amd-rhel9, rhelai1/bootc-azure-amd-rhel9, rhelai1/instructlab-amd-rhel9
    not affected: component 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

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
18 mo ago

Exploit prediction

0.87% chance of exploitation in the next 30 days, higher than 59% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
bitnami keydb
>=2.6.0, <6.2.18
>=7.0.0, <7.2.8
>=7.3.0, <7.4.3
6.2.18
7.2.8
7.4.3
bitnami redis
>=2.6.0, <6.2.18
>=7.0.0, <7.2.8
>=7.3.0, <6.2.18
>=7.2.0, <7.2.8
>=7.4.0, <7.4.3
6.2.18
7.2.8
7.4.3
bitnami valkey
<7.2.9
>=8.0.0, <8.0.3
>=8.1.0, <8.1.1
7.2.9
8.0.3
8.1.1

Affected products

  • redis redis

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling
Technology feeds

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.

The maintainers of redis/redis published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.