Linux: Incorrect Calculation
CVE-2026-53191 is a high-severity incorrect calculation vulnerability in Linux, with a CVSS 3.1 base score of 7.8 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 f40570fda3f3a1f96aeaa4aef665ba274b2810b5, 0bbc9481f970b0b4ddb08cfa464db1cc93b74b56, 4973232a67e4137ab9399f504f7f2bdd847f96d2 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 0.18% 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 f40570fda3f3a1f96aeaa4aef665ba274b2810b5 or 0bbc9481f970b0b4ddb08cfa464db1cc93b74b56 or 4973232a67e4137ab9399f504f7f2bdd847f96d2 or ed46f39c47eb5530a9c161481a2080d3a869cfaf, 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 | ae98dbf43d755b4e111fcd086e53939bef3e9a1a up to, but not including, f40570fda3f3a1f96aeaa4aef665ba274b2810b5; ae98dbf43d755b4e111fcd086e53939bef3e9a1a up to, but not including, 0bbc9481f970b0b4ddb08cfa464db1cc93b74b56; ae98dbf43d755b4e111fcd086e53939bef3e9a1a up to, but not including, 4973232a67e4137ab9399f504f7f2bdd847f96d2; ae98dbf43d755b4e111fcd086e53939bef3e9a1a up to, but not including, ed46f39c47eb5530a9c161481a2080d3a869cfaf; 6.12 | f40570fda3f3a1f96aeaa4aef665ba274b2810b5, 0bbc9481f970b0b4ddb08cfa464db1cc93b74b56, 4973232a67e4137ab9399f504f7f2bdd847f96d2, ed46f39c47eb5530a9c161481a2080d3a869cfaf |
| Linux | Linux Kernel | 6.12 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
- 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
- HighData or code can be modified at will.
- 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:H/A:H. Scored by CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: io_uring/net: inherit IORING_CQE_F_BUF_MORE across bundle recv retries When a bundle recv retries inside io_recv_finish(), the merge logic OR the saved cflags from the previous iteration with the cflags returned by the new iteration: cflags = req->cqe.flags | (cflags & CQE_F_MASK); Bits listed in CQE_F_MASK are inherited from the new iteration, and all other bits (notably IORING_CQE_F_BUFFER and the buffer ID) come from the saved cflags. Before this change CQE_F_MASK covered only IORING_CQE_F_SOCK_NONEMPTY and IORING_CQE_F_MORE. When using provided buffer rings (IOU_PBUF_RING_INC) with incremental mode, and bundle recv, io_kbuf_inc_commit() can leave the head ring entry partially consumed, __io_put_kbufs() then sets IORING_CQE_F_BUF_MORE on the returned cflags so userspace knows the buffer ID will be reused for subsequent completions. Because IORING_CQE_F_BUF_MORE was not in CQE_F_MASK, the merge above silently dropped it whenever the final retry iteration partially consumed the buffer, and the subsequent req->cqe.flags = cflags & ~CQE_F_MASK save would have left a stale IORING_CQE_F_BUF_MORE in the carried-over cflags had one been present. Userspace would then wrongfully advance it ring head past an entry the kernel still uses. Add IORING_CQE_F_BUF_MORE to CQE_F_MASK so it is both inherited from the new iteration into the user-visible CQE and stripped from the saved cflags between iterations.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Incorrect Calculation
The product performs a calculation that generates incorrect or unintended results that are later used in security-critical decisions or resource management.
How developers prevent this class of flaw
- Understand your programming language's underlying representation and how it interacts with numeric calculation. Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, not-a-number calculations, and how your language handles numbers that are too large or too small for its underlying representation.
- Perform input validation on any numeric input by ensuring that it is within the expected range. Enforce that the input meets both the minimum and maximum requirements for the expected range.
- Use the appropriate type for the desired action. For example, in C/C++, only use unsigned types for values that could never be negative, such as height, width, or other numbers related to quantity.
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 Incorrect Calculation vulnerabilities
- 7.5 High severity
- 8.6 High severity
- 8.3 High severity
- 9.1 Critical severity
- 9.8 Critical severity
- 7.8 High severity
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