CVE-2025-21042
CVE-2025-21042 is a security flaw in Samsung Mobile Devices, Samsung’s Android phones and tablets. Attackers can run their own code on Samsung Mobile Devices. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 10 Nov 2025.[1]
Samsung Mobile Devices is in things households have, such as phones, computers, browsers and everyday apps, so the fix matters at home as much as at work. Samsung has published a fix or advice.
Description
CISA calls it an out-of-bounds write in Samsung Mobile Devices. In its words: “Samsung mobile devices contain an out-of-bounds write vulnerability in libimagecodec.quram.so. This vulnerability could allow remote attackers to execute arbitrary code.”[1]
The underlying weakness is out-of-bounds write (CWE-787), in MITRE’s list of common software weaknesses.[2]
It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; Samsung’s advisory has them[3]. CISA names the product as Samsung Mobile Devices.
Every device with Samsung Mobile Devices needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 10 Nov 2025, 59 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 1 Dec 2025 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 36%. That’s in the top 2% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
Samsung has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.”[1]
- Update Samsung Mobile Devices now.On Android: Settings, then System or Software update. Phones only get these fixes while their maker still supports them. Then turn on automatic updates, so the next fix arrives on its own.
- If there’s no update, stop using it.CISA’s advice when a flaw being used in attacks has no fix is to stop using the product until it does.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 36%.[4] |
See also
Other Samsung Mobile Devices flaws
- CVE-2025-21043: out-of-bounds write ·
- CVE-2022-22265: use-after-free ·
- CVE-2021-25489: improper input validation ·
- CVE-2021-25487: out-of-bounds read ·
- CVE-2021-25395: race condition ·
- CVE-2021-25394: race condition ·
Other Samsung flaws
- CVE-2024-7399, Samsung MagicINFO 9 Server: path traversal ·
- CVE-2025-4632, Samsung MagicINFO 9 Server: path traversal ·
Other out-of-bounds write flaws
- CVE-2026-86950, Apple devices: out-of-bounds write ·
- CVE-2026-53266, Linux Kernel: out-of-bounds write ·
- CVE-2026-87491, Chrome and other Chromium browsers: out of bounds write ·
- CVE-2026-53362, Linux Kernel: unspecified ·
- CVE-2022-0995, Linux Kernel: out-of-bounds write ·
Every Samsung flaw on CISA’s list · Everything added in November 2025
References
- ^ Cybersecurity and Infrastructure Security Agency. “Samsung Mobile Devices Out-of-Bounds Write Vulnerability”. Known Exploited Vulnerabilities Catalog, added 10 Nov 2025.
- ^ National Institute of Standards and Technology. “CVE-2025-21042 Detail”. National Vulnerability Database, published 12 Sep 2025.
- ^ Samsung. Advisories and fixes: security.samsungmobile.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.356, percentile 98.5, 31 Oct 2026.
- CVE Program. “CVE-2025-21042”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.