Apple Multiple Products Integer Overflow
CVE-2021-30860 is a high-severity integer overflow or wraparound vulnerability in macOS from Apple, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists versions 11.6, 2021-005 as the first without the flaw, so updating macOS to one of those releases or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on November 3, 2021, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update macOS to 11.6 or 2021-005, whichever matches your release line, or a later version.
- Update watchOS to 7.6 or a later version.
- Update iOS to 14.8 or a later version.
- CISA's required action: Apply updates per vendor instructions.
- Read the advisory on support.apple.com for workarounds and exact fixed builds.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Apple | macOS | before 11.6; before 2021-005 | 11.6, 2021-005 |
| Apple | watchOS | before 7.6 | 7.6 |
| Apple | iOS | before 14.8 | 14.8 |
| Apple | iPadOS | before 14.8 | 14.8 |
| Apple | Iphone OS | before 12.5.5; 13.0 up to, but not including, 14.8 | 12.5.5, 14.8 |
| Apple | Mac OS X | 10.15 up to, but not including, 10.15.7; 10.15.7 | 10.15.7 |
| Xpdfreader | Xpdf | before 4.04 | 4.04 |
| Freedesktop | Poppler | before 22.09.0 | 22.09.0 |
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
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- 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:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | NVD |
| CVSS 3.1 | 7.8 | High | CISA (ADP) |
| CVSS 2.0 | 6.8 | Medium | NVD |
Official description
An integer overflow was addressed with improved input validation. This issue is fixed in Security Update 2021-005 Catalina, iOS 14.8 and iPadOS 14.8, macOS Big Sur 11.6, watchOS 7.6.2. Processing a maliciously crafted PDF may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Integer Overflow or Wraparound
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
How developers prevent this class of flaw
- Ensure that all protocols are strictly defined, such that all out-of-bounds behavior can be identified simply, and require strict conformance to the protocol.
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. If possible, choose a language or compiler that performs automatic bounds checking.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Use libraries or frameworks that make it easier to handle numbers without unexpected consequences. Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++).
More Integer Overflow or Wraparound vulnerabilities (CWE-190)
Timeline
- CVE record published.
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Deadline for US federal agencies to remediate, set by CISA.
- CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Third-party and government advisories
- seclists.org/fulldisclosure/2021/Sep/25Mailing List, Third Party Advisory
- seclists.org/fulldisclosure/2021/Sep/26Mailing List, Third Party Advisory
- seclists.org/fulldisclosure/2021/Sep/27Mailing List, Third Party Advisory
- seclists.org/fulldisclosure/2021/Sep/28Mailing List, Third Party Advisory
- seclists.org/fulldisclosure/2021/Sep/38Mailing List, Third Party Advisory
- seclists.org/fulldisclosure/2021/Sep/39Mailing List, Third Party Advisory
- seclists.org/fulldisclosure/2021/Sep/40Mailing List, Third Party Advisory
- seclists.org/fulldisclosure/2021/Sep/50Mailing List, Third Party Advisory
- security.gentoo.org/glsa/202209-21Third Party Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30860US Government Resource
Other references
- openwall.com/lists/oss-security/2022/09/02/11Mailing List
Other vulnerabilities in macOS
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Recent Integer Overflow or Wraparound vulnerabilities
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Google Chromium V8 Integer Overflow Exploited
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Linux Kernel Integer Overflow Exploited
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Adobe Flash Player Integer Overflow Exploited
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