Linux: Out-of-bounds Read
CVE-2025-39839 is a high-severity out-of-bounds read vulnerability in Linux, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 30fc47248f02b8a14a61df469e1da4704be1a19f, 1e36c6c8dc8023b4bbe9a16e819f9998b9b6a183, 5d334bce9fad58cf328d8fa14ea1fff855819863 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.26% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 30fc47248f02b8a14a61df469e1da4704be1a19f or 1e36c6c8dc8023b4bbe9a16e819f9998b9b6a183 or 5d334bce9fad58cf328d8fa14ea1fff855819863 or dce6c2aa70e94c04c523b375dfcc664d7a0a560a, whichever matches your release line, or a later version.
- Update RUGGEDCOM RST2428P to V3.3 or a later version.
- Update SCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 family to V3.3 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 2df5278b0267c799f3e877e8eeddbb6e93cda0bb up to, but not including, 30fc47248f02b8a14a61df469e1da4704be1a19f; 2df5278b0267c799f3e877e8eeddbb6e93cda0bb up to, but not including, 1e36c6c8dc8023b4bbe9a16e819f9998b9b6a183; 2df5278b0267c799f3e877e8eeddbb6e93cda0bb up to, but not including, 5d334bce9fad58cf328d8fa14ea1fff855819863; 2df5278b0267c799f3e877e8eeddbb6e93cda0bb up to, but not including, dce6c2aa70e94c04c523b375dfcc664d7a0a560a; 2df5278b0267c799f3e877e8eeddbb6e93cda0bb up to, but not including, bb37252c9af1cb250f34735ee98f80b46be3cef1; 2df5278b0267c799f3e877e8eeddbb6e93cda0bb up to, but not including, 20080709457bc1e920eb002483d7d981d9b2ac1c; 2df5278b0267c799f3e877e8eeddbb6e93cda0bb up to, but not including, a67c6397fcb7e842d3c595243049940970541c48; 2df5278b0267c799f3e877e8eeddbb6e93cda0bb up to, but not including, d77b6ff0ce35a6d0b0b7b9581bc3f76d041d4087; and 1 more ranges | 30fc47248f02b8a14a61df469e1da4704be1a19f, 1e36c6c8dc8023b4bbe9a16e819f9998b9b6a183, 5d334bce9fad58cf328d8fa14ea1fff855819863, dce6c2aa70e94c04c523b375dfcc664d7a0a560a, bb37252c9af1cb250f34735ee98f80b46be3cef1, 20080709457bc1e920eb002483d7d981d9b2ac1c |
| Siemens | RUGGEDCOM RST2428P | before V3.3 | V3.3 |
| Siemens | SCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 family | before V3.3 | V3.3 |
| Siemens | SCALANCE XCH328 | before V3.3 | V3.3 |
| Siemens | SCALANCE XCM324 | before V3.3 | V3.3 |
| Siemens | SCALANCE XCM328 | before V3.3 | V3.3 |
| Siemens | SCALANCE XCM332 | before V3.3 | V3.3 |
| Siemens | SCALANCE XRH334 (24 V DC, 8xFO, CC) | before V3.3 | V3.3 |
| Siemens | SCALANCE XRM334 (230 V AC, 12xFO) | before V3.3 | V3.3 |
| Siemens | SCALANCE XRM334 (230 V AC, 8xFO) | before V3.3 | V3.3 |
| Siemens | SCALANCE XRM334 (230V AC, 2x10G, 24xSFP, 8xSFP+) | before V3.3 | V3.3 |
| Siemens | SCALANCE XRM334 (24 V DC, 12xFO) | before V3.3 | V3.3 |
| Siemens | SCALANCE XRM334 (24 V DC, 8xFO) | before V3.3 | V3.3 |
| Siemens | SCALANCE XRM334 (24V DC, 2x10G, 24xSFP, 8xSFP+) | before V3.3 | V3.3 |
| Siemens | SCALANCE XRM334 (2x230 V AC, 12xFO) | before V3.3 | V3.3 |
| Siemens | SCALANCE XRM334 (2x230 V AC, 8xFO) | before V3.3 | V3.3 |
| Siemens | SCALANCE XRM334 (2x230V AC, 2x10G, 24xSFP, 8xSFP+) | before V3.3 | V3.3 |
| Siemens | SIMATIC CN 4100 | before V5.0 | V5.0 |
| Linux | Linux Kernel | 3.10 up to, but not including, 5.4.299; 5.5 up to, but not including, 5.10.243; 5.11 up to, but not including, 5.15.192; 5.16 up to, but not including, 6.1.151; 6.2 up to, but not including, 6.6.105; 6.7 up to, but not including, 6.12.46; 6.13 up to, but not including, 6.16.6; 6.17 | 5.4.299, 5.10.243, 5.15.192, 6.1.151, 6.6.105, 6.12.46 |
| Debian | Debian Linux | 11.0 | Not stated |
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
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.8 | High | CNA |
| CVSS 3.1 | 7.1 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: batman-adv: fix OOB read/write in network-coding decode batadv_nc_skb_decode_packet() trusts coded_len and checks only against skb->len. XOR starts at sizeof(struct batadv_unicast_packet), reducing payload headroom, and the source skb length is not verified, allowing an out-of-bounds read and a small out-of-bounds write. Validate that coded_len fits within the payload area of both destination and source sk_buffs before XORing.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that provides appropriate memory abstractions.
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/1e36c6c8dc8023b4bbe9a16e819f9998b9b6a183
- git.kernel.org/stable/c/20080709457bc1e920eb002483d7d981d9b2ac1c
- git.kernel.org/stable/c/30fc47248f02b8a14a61df469e1da4704be1a19f
- git.kernel.org/stable/c/5d334bce9fad58cf328d8fa14ea1fff855819863
- git.kernel.org/stable/c/a67c6397fcb7e842d3c595243049940970541c48
- git.kernel.org/stable/c/bb37252c9af1cb250f34735ee98f80b46be3cef1
- git.kernel.org/stable/c/d77b6ff0ce35a6d0b0b7b9581bc3f76d041d4087
- git.kernel.org/stable/c/dce6c2aa70e94c04c523b375dfcc664d7a0a560a
Third-party and government advisories
- lists.debian.org/debian-lts-announce/2025/10/msg00007.htmlMailing List, Third Party Advisory
- lists.debian.org/debian-lts-announce/2025/10/msg00008.htmlMailing List, Third Party Advisory
Other references
Recent Out-of-bounds Read vulnerabilities
- 7.1 High severity
- 7.1 High severity
- 7.1 High severity
- 7.1 High severity
- 7.1 High severity
- 7.8 High severity
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