CVE-2021-32626

Redis is an open source, in-memory database that persists on disk. In affected versions specially crafted Lua scripts executing in Redis can cause the heap-based Lua stack to be overflowed, due to incomplete checks for this condition. This can result with heap corruption and potentially remote code execution. This problem exists in all versions of Redis with Lua scripting support, starting from 2.6. The problem is fixed in versions 6.2.6, 6.0.16 and 5.0.14. For users unable to update an additional workaround to mitigate the problem without patching the redis-server executable is to prevent users from executing Lua scripts. This can be done using ACL to restrict EVAL and EVALSHA commands.

Weakness

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

Affected Software

Name	Vendor	Start Version	End Version
Redis	Redis	2.6 (including)	5.0.14 (excluding)
Redis	Redis	6.0.0 (including)	6.0.16 (excluding)
Redis	Redis	6.2.0 (including)	6.2.6 (excluding)
Red Hat Advanced Cluster Management for Kubernetes 2.3 for RHEL 8	RedHat	rhacm2/redisgraph-tls-rhel8:v2.3.3-3	*
Red Hat Enterprise Linux 8	RedHat	redis:5-8040020211011074037.522a0ee4	*
Red Hat Enterprise Linux 8	RedHat	redis:6-8040020211011082941.522a0ee4	*
Red Hat Enterprise Linux 8.1 Extended Update Support	RedHat	redis:5-8010020211011065007.c27ad7f8	*
Red Hat Enterprise Linux 8.2 Extended Update Support	RedHat	redis:5-8020020211011071901.4cda2c84	*
Red Hat OpenStack Platform 10.0 (Newton)	RedHat	redis-0:3.2.8-5.el7ost	*
Red Hat OpenStack Platform 13.0 - ELS	RedHat	redis-0:3.2.8-5.el7ost	*
Red Hat OpenStack Platform 13.0 (Queens) for RHEL 7.6 EUS	RedHat	redis-0:3.2.8-5.el7ost	*
Red Hat Software Collections for Red Hat Enterprise Linux 7	RedHat	rh-redis5-redis-0:5.0.5-3.el7	*
Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUS	RedHat	rh-redis5-redis-0:5.0.5-3.el7	*
Redis	Ubuntu	bionic	*
Redis	Ubuntu	esm-apps/bionic	*
Redis	Ubuntu	esm-apps/focal	*
Redis	Ubuntu	esm-apps/xenial	*
Redis	Ubuntu	esm-infra-legacy/trusty	*
Redis	Ubuntu	focal	*
Redis	Ubuntu	hirsute	*
Redis	Ubuntu	impish	*
Redis	Ubuntu	trusty	*
Redis	Ubuntu	trusty/esm	*
Redis	Ubuntu	upstream	*
Redis	Ubuntu	xenial	*

Potential Mitigations

Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking.
D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail.
Run or compile the software using features or extensions that randomly arrange the positions of a program’s executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code.
Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as “rebasing” (for Windows) and “prelinking” (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking.
For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335].

https://cwe.mitre.org/data/definitions/92.html

NVD	https://nvd.nist.gov/vuln/detail/CVE-2021-32626
CWE	https://cwe.mitre.org/data/definitions/122.html

Heap-based Buffer Overflow

Weakness

Affected Software

Potential Mitigations

References

CVE-2021-32626

Heap-based Buffer Overflow

Weakness

Affected Software

Potential Mitigations

Related Attack Patterns

References