Is CVE-2026-20657 in the CISA KEV catalog?

No. CVE-2026-20657 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-20657?

CVE-2026-20657 has a CVSS v3 base score of 6.5 (MEDIUM).

What is the EPSS score for CVE-2026-20657?

CVE-2026-20657 has an EPSS score of 0.54% (42th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-20657?

Update iOS to 26.4 or later. Fixes are available for 5 affected products.

CVE & CISA-KEV Catalog

CVE-2026-20657

MEDIUM

6.5

CVSS v3

NVD

Description

A buffer overflow issue was addressed with improved memory handling. This issue is fixed in iOS 18.7.7 and iPadOS 18.7.7, iOS 26.4 and iPadOS 26.4, macOS Sequoia 15.7.5, macOS Sonoma 14.8.5, macOS Tahoe 26.4, visionOS 26.4. Parsing a maliciously crafted file may lead to an unexpected app termination.

CWE-119Buffer Overflow CWE-125Out-of-bounds Read CWE-787Out-of-bounds Write

How to fix

Remediation Available

iOSApple

Fixed in:26.4126792

Fixed in:18.7.7126793

macOS SequoiaApple

Fixed in:15.7.5126795

macOS SonomaApple

Fixed in:14.8.5126796

macOS TahoeApple

Fixed in:26.4126794

visionOSApple

Fixed in:26.4126799

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Exploit Intelligence

0.54%probability of exploitation in 30 days

42ndpercentile

Moderate risk: more likely to be exploited than 42% of all known CVEs.

References

Vendor Advisory3

Other references3

Related Vulnerabilities

Other CWE-119 (Buffer Overflow) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-4966	Critical	9.4	100%	KEV + Ransom	Fix
CVE-2017-11882	High	7.8	100%	KEV + Ransom	-
CVE-2020-0796	Critical	10.0	100%	KEV + Ransom	-
CVE-2008-4250	Critical	9.8	99%	KEV	-
CVE-2017-15944	Critical	9.8	98%	KEV	Fix
CVE-2015-0014	High	10.0	97%	-	-

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-11.