CyberSecBulletin
CVE-2021-22991Exploited in the wildNVD status: Analyzed

F5 BIG-IP Traffic Management Microkernel Buffer Overflow

Published Updated By the CyberSecBulletin desk

CVE-2021-22991 is a critical-severity improper restriction of operations within the bounds of a memory buffer vulnerability in BIG-IP, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. CISA added it to the Known Exploited Vulnerabilities catalogue on January 18, 2022, which means attacks have been observed in the wild.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Update Big-ip Access Policy Manager to 12.1.5.3 or 13.1.3.6 or 14.1.4 or 15.1.2.1, whichever matches your release line, or a later version.
  2. Update Big-ip Advanced Firewall Manager to 12.1.5.3 or 13.1.3.6 or 14.1.4 or 15.1.2.1, whichever matches your release line, or a later version.
  3. Update Big-ip Advanced Web Application Firewall to 12.1.5.3 or 13.1.3.6 or 14.1.4 or 15.1.2.1, whichever matches your release line, or a later version.
  4. CISA's required action: Apply updates per vendor instructions.
  5. Read the advisory on support.f5.com for workarounds and exact fixed builds.
  6. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
BIG-IPBIG-IPNot specified in the recordNot stated
F5Big-ip Access Policy Manager12.1.0 up to, but not including, 12.1.5.3; 13.1.0 up to, but not including, 13.1.3.6; 14.1.0 up to, but not including, 14.1.4; 15.1.0 up to, but not including, 15.1.2.1; 16.0.0 up to, but not including, 16.0.1.112.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
F5Big-ip Advanced Firewall Manager12.1.0 up to, but not including, 12.1.5.3; 13.1.0 up to, but not including, 13.1.3.6; 14.1.0 up to, but not including, 14.1.4; 15.1.0 up to, but not including, 15.1.2.1; 16.0.0 up to, but not including, 16.0.1.112.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
F5Big-ip Advanced Web Application Firewall12.1.0 up to, but not including, 12.1.5.3; 13.1.0 up to, but not including, 13.1.3.6; 14.1.0 up to, but not including, 14.1.4; 15.1.0 up to, but not including, 15.1.2.1; 16.0.0 up to, but not including, 16.0.1.112.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
F5Big-ip Analytics12.1.0 up to, but not including, 12.1.5.3; 13.1.0 up to, but not including, 13.1.3.6; 14.1.0 up to, but not including, 14.1.4; 15.1.0 up to, but not including, 15.1.2.1; 16.0.0 up to, but not including, 16.0.1.112.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
F5Big-ip Application Acceleration Manager12.1.0 up to, but not including, 12.1.5.3; 13.1.0 up to, but not including, 13.1.3.6; 14.1.0 up to, but not including, 14.1.4; 15.1.0 up to, but not including, 15.1.2.1; 16.0.0 up to, but not including, 16.0.1.112.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
F5Big-ip Application Security Manager12.1.0 up to, but not including, 12.1.5.3; 13.1.0 up to, but not including, 13.1.3.6; 14.1.0 up to, but not including, 14.1.4; 15.1.0 up to, but not including, 15.1.2.1; 16.0.0 up to, but not including, 16.0.1.112.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
F5Big-ip Ddos Hybrid Defender12.1.0 up to, but not including, 12.1.5.3; 13.1.0 up to, but not including, 13.1.3.6; 14.1.0 up to, but not including, 14.1.4; 15.1.0 up to, but not including, 15.1.2.1; 16.0.0 up to, but not including, 16.0.1.112.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
F5Big-ip Domain Name System12.1.0 up to, but not including, 12.1.5.3; 13.1.0 up to, but not including, 13.1.3.6; 14.1.0 up to, but not including, 14.1.4; 15.1.0 up to, but not including, 15.1.2.1; 16.0.0 up to, but not including, 16.0.1.112.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
F5Big-ip Fraud Protection Service12.1.0 up to, but not including, 12.1.5.3; 13.1.0 up to, but not including, 13.1.3.6; 14.1.0 up to, but not including, 14.1.4; 15.1.0 up to, but not including, 15.1.2.1; 16.0.0 up to, but not including, 16.0.1.112.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
F5Big-ip Global Traffic Manager12.1.0 up to, but not including, 12.1.5.3; 13.1.0 up to, but not including, 13.1.3.6; 14.1.0 up to, but not including, 14.1.4; 15.1.0 up to, but not including, 15.1.2.1; 16.0.0 up to, but not including, 16.0.1.112.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
F5Big-ip Link Controller12.1.0 up to, but not including, 12.1.5.3; 13.1.0 up to, but not including, 13.1.3.6; 14.1.0 up to, but not including, 14.1.4; 15.1.0 up to, but not including, 15.1.2.1; 16.0.0 up to, but not including, 16.0.1.112.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
F5Big-ip Local Traffic Manager12.1.0 up to, but not including, 12.1.5.3; 13.1.0 up to, but not including, 13.1.3.6; 14.1.0 up to, but not including, 14.1.4; 15.1.0 up to, but not including, 15.1.2.1; 16.0.0 up to, but not including, 16.0.1.112.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
F5Big-ip Policy Enforcement Manager12.1.0 up to, but not including, 12.1.5.3; 13.1.0 up to, but not including, 13.1.3.6; 14.1.0 up to, but not including, 14.1.4; 15.1.0 up to, but not including, 15.1.2.1; 16.0.0 up to, but not including, 16.0.1.112.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1
F5SSL Orchestrator12.1.0 up to, but not including, 12.1.5.3; 13.1.0 up to, but not including, 13.1.3.6; 14.1.0 up to, but not including, 14.1.4; 15.1.0 up to, but not including, 15.1.2.1; 16.0.0 up to, but not including, 16.0.1.112.1.5.3, 13.1.3.6, 14.1.4, 15.1.2.1, 16.0.1.1

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.19.8CriticalNVD
CVSS 3.19.8CriticalCISA (ADP)
CVSS 2.06.8MediumNVD

Official description

On BIG-IP versions 16.0.x before 16.0.1.1, 15.1.x before 15.1.2.1, 14.1.x before 14.1.4, 13.1.x before 13.1.3.6, and 12.1.x before 12.1.5.3, undisclosed requests to a virtual server may be incorrectly handled by the Traffic Management Microkernel (TMM) URI normalization, which may trigger a buffer overflow, resulting in a DoS attack. In certain situations, it may theoretically allow bypass of URL based access control or remote code execution (RCE). Note: Software versions which have reached End of Software Development (EoSD) are not evaluated.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Restriction of Operations within the Bounds of a Memory Buffer

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • 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 discusses canary-based detection in detail.

More Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerabilities (CWE-119)

Timeline

  1. CVE record published.
  2. Added to CISA's Known Exploited Vulnerabilities catalogue.
  3. Deadline for US federal agencies to remediate, set by CISA.
  4. CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: total).
  5. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Other vulnerabilities in BIG-IP

All BIG-IP vulnerabilities

Recent Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerabilities

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