CVE-2020-9819
A memory consumption issue was addressed with improved memory handling. This issue is fixed in iOS 13.5 and iPadOS 13.5, iOS 12.4.7, watchOS 6.2.5, watchOS 5.3.7. Processing a maliciously crafted mail message may lead to heap corruption.
- CVSS
- 4.3Mediumscored by CISA
- Exploited in the wild
- Yes, in CISA KEV since 3 Nov 2021CISA deadline for US federal agencies: 3 May 2022
- EPSS
- 2.2%chance of exploitation in the next 30 daystop 18% of scored CVEsFIRST score of 11 Nov 2026
- Fix
- Patch availablesee the advisories in the references
- Published
- 9 Jun 2020analysed here 12 Nov 2026
Do first. Apply updates per vendor instructions. (CISA's required action for this KEV entry)
Summary
Triage
The summary, impact and action text on this page are written by our AI analysis pipeline, or taken from the NVD description when a CVE was imported from NVD. They are not the vendor's wording: check them against the sources. A longer AI executive summary and technical analysis are generated for signed-in accounts on the Max plan.
Affected products
| Product | Affected versions | Vendor says fixed in |
|---|---|---|
| Apple iOS | < iOS 13.5 and iPadOS 13.5Vendor says fixed in: not stated | |
| Apple iOS-1 | < iOS 12.4.7Vendor says fixed in: not stated | |
| Apple watchOS | < watchOS 6.2.5Vendor says fixed in: not stated | |
| Apple watchOS-1 | < watchOS 5.3.7Vendor says fixed in: not stated |
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.
Products named in our analysis
- apple:ipados
- apple:iphone_os
- apple:watchos
Fix and mitigation
WAF and other mitigations
Can a WAF block it? No. This is an out-of-bounds write, a memory-corruption bug. Generic WAF rules do not recognise the input that triggers it; only a rule written for this specific CVE can, and only if the triggering request has a recognisable shape.
Also consider: patch
Based on the weakness type only; no CVE-specific evidence yet. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.
Remediation steps (AI-written)
Step-by-step remediation is generated for accounts on the Max plan, for CVEs that match a technology in their stack. Add this technology to your stack to see the fix checklist.
Exploitation evidence
- CISA KEV catalog
- Listed since 3 Nov 2021.
- CISA due date
- 3 May 2022, the remediation deadline for US federal agencies
- CISA required action
- Apply updates per vendor instructions.
- Public exploit code
- None on record in Exploit-DB, Metasploit, Nuclei templates or PoC-in-GitHub.
- CISA SSVC
- exploitation active, automatable no, technical impact totalAssessed by CISA 19 Aug 2025 (SSVC 2.0.3). Exploitation is none, poc (public proof of concept) or active.
Timeline
- 9 Jun 2020Published
- 3 Nov 2021Added to CISA KEV (exploited in the wild)511 days (about 1 year) later
- 3 May 2022CISA remediation due date (US federal agencies)181 days (about 6 months) later
- 19 Aug 2025CISA SSVC assessment: exploitation active1,204 days (about 3 years) later
- 20 Dec 2025CVE record last updated123 days (about 4 months) later
- 12 Nov 2026Analysed by vulneraibility.com327 days (about 11 months) later
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
| Metric | Value | What it means |
|---|---|---|
| Attack vector | NetworkReachable over the internet or any routable network. | Reachable over the internet or any routable network. |
| Attack complexity | LowRepeatable attack, no special conditions. | Repeatable attack, no special conditions. |
| Privileges required | NoneThe attacker needs no prior access. | The attacker needs no prior access. |
| User interaction | RequiredA victim must click, open or otherwise cooperate. | A victim must click, open or otherwise cooperate. |
| Scope | UnchangedImpact stays within the vulnerable component. | Impact stays within the vulnerable component. |
| Confidentiality | NoneNo data disclosure. | No data disclosure. |
| Integrity | NoneNo unauthorised modification. | No unauthorised modification. |
| Availability | LowPartial degradation possible. | Partial degradation possible. |
Common questions
Is CVE-2020-9819 being exploited?
Yes. CVE-2020-9819 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2020-9819?
CVE-2020-9819 is rated Medium with a CVSS score of 4.3. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2020-9819?
Yes. A fix has been recorded for CVE-2020-9819. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2020-9819 affect?
CVE-2020-9819 affects apple:ipados, apple:iphone_os, apple:watchos. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
References
5 references in the CVE record, grouped by the tags the record gives them.
Other links (5)
- support.apple.com /HT211168
- support.apple.com /HT211175
- support.apple.com /HT211169
- support.apple.com /HT211176
- cisa.gov /known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-9819
Where the data on this page comes from
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- CISA KEV catalog: exploitation, date added, due date
- CISA Vulnrichment (ADP): SSVC decision points
- FIRST EPSS: exploit probability and percentile
Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.
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