Linux: Improper Validation of Specified Quantity in Input
CVE-2026-63869 is a high-severity improper validation of specified quantity in input vulnerability in Linux, with a CVSS 3.1 base score of 7.6 out of 10. It can be exploited from the same local network by an attacker with a low-privileged account, without any action from a user. The record lists versions f6d3dc8e8492bf8435e0b23c99472af7bafd6b44, 9b40c59bab08f2a99abf969cc0bb92fa49de004b, 033ce021a220913ac02416fcb5ac883a9ff8b6c7 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 f6d3dc8e8492bf8435e0b23c99472af7bafd6b44 or 9b40c59bab08f2a99abf969cc0bb92fa49de004b or 033ce021a220913ac02416fcb5ac883a9ff8b6c7 or 6c0cf89f36ac0c0fd8687a4ccdce2efb23a9c663, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.94 or 6.18.36 or 7.0.13, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | ef246a1480cc484cd2aeda75737cb0848616ddf3 up to, but not including, f6d3dc8e8492bf8435e0b23c99472af7bafd6b44; ef246a1480cc484cd2aeda75737cb0848616ddf3 up to, but not including, 9b40c59bab08f2a99abf969cc0bb92fa49de004b; ef246a1480cc484cd2aeda75737cb0848616ddf3 up to, but not including, 033ce021a220913ac02416fcb5ac883a9ff8b6c7; ef246a1480cc484cd2aeda75737cb0848616ddf3 up to, but not including, 6c0cf89f36ac0c0fd8687a4ccdce2efb23a9c663; 6.7 | f6d3dc8e8492bf8435e0b23c99472af7bafd6b44, 9b40c59bab08f2a99abf969cc0bb92fa49de004b, 033ce021a220913ac02416fcb5ac883a9ff8b6c7, 6c0cf89f36ac0c0fd8687a4ccdce2efb23a9c663 |
| Linux | Linux Kernel | 6.7 up to, but not including, 6.12.94; 6.13 up to, but not including, 6.18.36; 6.19 up to, but not including, 7.0.13; 7.1 | 6.12.94, 6.18.36, 7.0.13 |
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
- AdjacentThe attacker must be on the same local network segment.
- 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
- HighData or code can be modified at will.
- Availability
- LowPerformance or availability is reduced.
Vector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L. Scored by CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: limit injected antenna index in ieee80211_parse_tx_radiotap When parsing the radiotap header of an injected frame, ieee80211_parse_tx_radiotap() uses the IEEE80211_RADIOTAP_ANTENNA value directly as a shift count: info->control.antennas |= BIT(*iterator.this_arg); *iterator.this_arg is an 8-bit value taken straight from the frame supplied by userspace, so BIT() can be asked to shift by up to 255. That is undefined behaviour on the unsigned long and is reported by UBSAN: UBSAN: shift-out-of-bounds in net/mac80211/tx.c:2174:30 shift exponent 235 is too large for 64-bit type 'unsigned long' Call Trace: ieee80211_parse_tx_radiotap+0xadb/0x1950 net/mac80211/tx.c:2174 ieee80211_monitor_start_xmit+0xb1f/0x1250 net/mac80211/tx.c:2451 ... packet_sendmsg+0x3eb6/0x50f0 net/packet/af_packet.c:3109 info->control.antennas is a 2-bit bitmap (u8 antennas:2), so only antenna indices 0 and 1 can ever be represented. Ignore any larger value instead of shifting out of bounds.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Validation of Specified Quantity in Input
The product receives input that is expected to specify a quantity (such as size or length), but it does not validate or incorrectly validates that the quantity has the required properties.
More Improper Validation of Specified Quantity in Input vulnerabilities (CWE-1284)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Improper Validation of Specified Quantity in Input vulnerabilities
- 8.3 High severity
- 8.3 High severity
- 8.2 High severity
- 7.5 High severity
- 7.3 High severity
- 8.5 High severity
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