Linux: Out-of-bounds Read
CVE-2026-46033 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 77f59fb2d3aa33e90ec6cbbf45dcfb20ab82b1a9, 2f31cd1e64a079c845bca31d2da7b3c90a311726, d4c6a6d08e70bb1083c7c405fc7faacbf19aebc0 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 0.14% 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 77f59fb2d3aa33e90ec6cbbf45dcfb20ab82b1a9 or 2f31cd1e64a079c845bca31d2da7b3c90a311726 or d4c6a6d08e70bb1083c7c405fc7faacbf19aebc0 or b69933e97efea238ebbfcf70c2b1be1cd03f13e3, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.258 or 5.15.209 or 6.1.175 or 6.6.140, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | f15f05b0a5de667c821a9727c33bce9d1d9b26dd up to, but not including, 77f59fb2d3aa33e90ec6cbbf45dcfb20ab82b1a9; f15f05b0a5de667c821a9727c33bce9d1d9b26dd up to, but not including, 2f31cd1e64a079c845bca31d2da7b3c90a311726; f15f05b0a5de667c821a9727c33bce9d1d9b26dd up to, but not including, d4c6a6d08e70bb1083c7c405fc7faacbf19aebc0; f15f05b0a5de667c821a9727c33bce9d1d9b26dd up to, but not including, b69933e97efea238ebbfcf70c2b1be1cd03f13e3; f15f05b0a5de667c821a9727c33bce9d1d9b26dd up to, but not including, 67f1f0933cc3d78dde222842bcad2778ec7a0b88; f15f05b0a5de667c821a9727c33bce9d1d9b26dd up to, but not including, b42821c15445f93daea3e76ada682b2b7181c476; f15f05b0a5de667c821a9727c33bce9d1d9b26dd up to, but not including, 9aff81e8217e9de2929084b03b3c7f81988c112b; f15f05b0a5de667c821a9727c33bce9d1d9b26dd up to, but not including, 5db6ef9847717329f12c5ea8aba7e9f588a980c0; and 1 more ranges | 77f59fb2d3aa33e90ec6cbbf45dcfb20ab82b1a9, 2f31cd1e64a079c845bca31d2da7b3c90a311726, d4c6a6d08e70bb1083c7c405fc7faacbf19aebc0, b69933e97efea238ebbfcf70c2b1be1cd03f13e3, 67f1f0933cc3d78dde222842bcad2778ec7a0b88, b42821c15445f93daea3e76ada682b2b7181c476 |
| Red Hat | Red Hat Enterprise Linux 10 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 6 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 7 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 8 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 9 | Not specified in the record | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 TM MFP - GNU/Linux subsystem | all versions | Not stated |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Linux | Linux Kernel | 4.11 up to, but not including, 5.10.258; 5.11 up to, but not including, 5.15.209; 5.16 up to, but not including, 6.1.175; 6.2 up to, but not including, 6.6.140; 6.7 up to, but not including, 6.12.86; 6.13 up to, but not including, 6.18.27; 6.19 up to, but not including, 7.0.4; 7.1 | 5.10.258, 5.15.209, 6.1.175, 6.6.140, 6.12.86, 6.18.27 |
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 | 7.1 | High | NVD |
| CVSS 3.1 | 7.1 | High | CNA |
Official description
In the Linux kernel, the following vulnerability has been resolved: crypto: authencesn - reject short ahash digests during instance creation authencesn requires either a zero authsize or an authsize of at least 4 bytes because the ESN encrypt/decrypt paths always move 4 bytes of high-order sequence number data at the end of the authenticated data. While crypto_authenc_esn_setauthsize() already rejects explicit non-zero authsizes in the range 1..3, crypto_authenc_esn_create() still copied auth->digestsize into inst->alg.maxauthsize without validating it. The AEAD core then initialized the tfm's default authsize from that value. As a result, selecting an ahash with digest size 1..3, such as cbcmac(cipher_null), exposed authencesn instances whose default authsize was invalid even though setauthsize() would have rejected the same value. AF_ALG could then trigger the ESN tail handling with a too-short tag and hit an out-of-bounds access. Reject authencesn instances whose ahash digest size is in the invalid non-zero range 1..3 so that no tfm can inherit an unsupported default authsize.
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.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/2f31cd1e64a079c845bca31d2da7b3c90a311726
- git.kernel.org/stable/c/5db6ef9847717329f12c5ea8aba7e9f588a980c0
- git.kernel.org/stable/c/67f1f0933cc3d78dde222842bcad2778ec7a0b88
- git.kernel.org/stable/c/77f59fb2d3aa33e90ec6cbbf45dcfb20ab82b1a9
- git.kernel.org/stable/c/9aff81e8217e9de2929084b03b3c7f81988c112b
- git.kernel.org/stable/c/b42821c15445f93daea3e76ada682b2b7181c476
- git.kernel.org/stable/c/b69933e97efea238ebbfcf70c2b1be1cd03f13e3
- git.kernel.org/stable/c/d4c6a6d08e70bb1083c7c405fc7faacbf19aebc0
Other references
- access.redhat.com/security/cve/CVE-2026-46033
- bugzilla.redhat.com/show_bug.cgi?id=2482000
- cert-portal.siemens.com/productcert/html/ssa-019113.html
- cert-portal.siemens.com/productcert/html/ssa-457936.html
- cert-portal.siemens.com/productcert/html/ssa-784472.html
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-46033.json
Recent Out-of-bounds Read vulnerabilities
- 7.1 High severity
- 7.1 High severity
- 7.1 High severity
- 7.1 High severity
- 8.2 High severity
- 7.1 High severity
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