CVE-2021-25487
CVE-2021-25487 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 29 Jun 2023.[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. Fixed in version SMR Oct-2021 Release 1 of Samsung Mobile Devices.
Description
CISA calls it an out-of-bounds read in Samsung Mobile Devices. In its words: “Samsung mobile devices contain an out-of-bounds read vulnerability within the modem interface driver due to a lack of boundary checking of a buffer in set_skb_priv(), leading to remote code execution by dereference of an invalid function pointer.”[1]
The underlying weakness is out-of-bounds read (CWE-125), in MITRE’s list of common software weaknesses.[2]
It scores 7.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record lists one fixed version: everything before it is affected.[2]
| Product | Fixed in |
|---|---|
| Samsung Mobile Devices | SMR Oct-2021 Release 1 |
Every device with Samsung Mobile Devices needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 29 Jun 2023, 631 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 20 Jul 2023 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 under 1%. That’s in the top 50% 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 updates per vendor instructions or discontinue use of the product if updates 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.
- Check you’re on SMR Oct-2021 Release 1 or later.Fixed in version SMR Oct-2021 Release 1 of Samsung Mobile Devices. Anything older is what attackers are going after.
- 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 7.8.[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 under 1%.[4] |
See also
Other Samsung Mobile Devices flaws
- CVE-2025-21042: out-of-bounds write ·
- CVE-2025-21043: out-of-bounds write ·
- CVE-2022-22265: use-after-free ·
- CVE-2021-25489: improper input validation ·
- 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 read flaws
- CVE-2023-36424, Microsoft Windows: out-of-bounds read ·
- CVE-2026-3055, Citrix NetScaler: out-of-bounds read ·
- CVE-2025-5777, Citrix NetScaler ADC and Gateway: out-of-bounds read ·
- CVE-2025-5419, Chrome and other Chromium browsers: out-of-bounds read and write ·
- CVE-2024-53150, Linux Kernel: out-of-bounds read ·
Added the same day
- CVE-2021-25489, Samsung Mobile Devices: improper input validation ·
- CVE-2021-25395, Samsung Mobile Devices: race condition ·
- CVE-2021-25394, Samsung Mobile Devices: race condition ·
- CVE-2021-25372, Samsung Mobile Devices: improper boundary check ·
- CVE-2021-25371, Samsung Mobile Devices: unspecified ·
Every Samsung flaw on CISA’s list · Everything added in June 2023
References
- ^ Cybersecurity and Infrastructure Security Agency. “Samsung Mobile Devices Out-of-Bounds Read Vulnerability”. Known Exploited Vulnerabilities Catalog, added 29 Jun 2023.
- ^ National Institute of Standards and Technology. “CVE-2021-25487 Detail”. National Vulnerability Database, published 6 Oct 2021.
- ^ Samsung. Advisories and fixes: security.samsungmobile.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.006, percentile 50.4, 31 Oct 2026.
- CVE Program. “CVE-2021-25487”. 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.