Linux: Use of Incorrect Byte Ordering
CVE-2026-46306 is a high-severity use of incorrect byte ordering vulnerability in Linux, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions e7c811ca372d53c2be7d01a1614e71fae1054836, abc5bc84e0f2edc7ea2d437afa6ef3fe1fc43200, 18ae9eacfc95cc715c0606b2c86e8aa8a86cf3e3 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 0.45% 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 e7c811ca372d53c2be7d01a1614e71fae1054836 or abc5bc84e0f2edc7ea2d437afa6ef3fe1fc43200 or 18ae9eacfc95cc715c0606b2c86e8aa8a86cf3e3 or db104b0d8a7856397c0469d83a4289adf7c54863, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.1.175 or 6.6.140 or 6.12.88 or 6.18.30, whichever matches your release line, or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 10f665b52a75df6eb26ddebbbc072ee264183731 up to, but not including, e7c811ca372d53c2be7d01a1614e71fae1054836; d7e541e86122d21f71eb71c5dfa7fb1eb6623fe8 up to, but not including, abc5bc84e0f2edc7ea2d437afa6ef3fe1fc43200; 46126db9c86110e5fc1e369b9bb89735ddefdae4 up to, but not including, 18ae9eacfc95cc715c0606b2c86e8aa8a86cf3e3; 46126db9c86110e5fc1e369b9bb89735ddefdae4 up to, but not including, db104b0d8a7856397c0469d83a4289adf7c54863; 46126db9c86110e5fc1e369b9bb89735ddefdae4 up to, but not including, 6044392d9cace3a3672b02c8bc7d38b502e51734; 46126db9c86110e5fc1e369b9bb89735ddefdae4 up to, but not including, 0d00b9015069712944934bab09eaa6c542143049; 46126db9c86110e5fc1e369b9bb89735ddefdae4 up to, but not including, 7c93f353eab4ea911e394630f07d72e040a729d8; 46126db9c86110e5fc1e369b9bb89735ddefdae4 up to, but not including, d6c19b31a3c1d519fabdcf0aa239e6b6109b9473; and 1 more ranges | e7c811ca372d53c2be7d01a1614e71fae1054836, abc5bc84e0f2edc7ea2d437afa6ef3fe1fc43200, 18ae9eacfc95cc715c0606b2c86e8aa8a86cf3e3, db104b0d8a7856397c0469d83a4289adf7c54863, 6044392d9cace3a3672b02c8bc7d38b502e51734, 0d00b9015069712944934bab09eaa6c542143049 |
| 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 | 6.0 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, 6.12.88; 6.13 up to, but not including, 6.18.30; 6.19 up to, but not including, 7.0.7 | 6.1.175, 6.6.140, 6.12.88, 6.18.30, 7.0.7 |
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
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: flow_dissector: do not dissect PPPoE PFC frames RFC 2516 Section 7 states that Protocol Field Compression (PFC) is NOT RECOMMENDED for PPPoE. In practice, pppd does not support negotiating PFC for PPPoE sessions, and the flow dissector driver has assumed an uncompressed frame until the blamed commit. During the review process of that commit [1], support for PFC is suggested. However, having a compressed (1-byte) protocol field means the subsequent PPP payload is shifted by one byte, causing 4-byte misalignment for the network header and an unaligned access exception on some architectures. The exception can be reproduced by sending a PPPoE PFC frame to an ethernet interface of a MIPS board, with RPS enabled, even if no PPPoE session is active on that interface: $ 0 : 00000000 80c40000 00000000 85144817 $ 4 : 00000008 00000100 80a75758 81dc9bb8 $ 8 : 00000010 8087ae2c 0000003d 00000000 $12 : 000000e0 00000039 00000000 00000000 $16 : 85043240 80a75758 81dc9bb8 00006488 $20 : 0000002f 00000007 85144810 80a70000 $24 : 81d1bda0 00000000 $28 : 81dc8000 81dc9aa8 00000000 805ead08 Hi : 00009d51 Lo : 2163358a epc : 805e91f0 __skb_flow_dissect+0x1b0/0x1b50 ra : 805ead08 __skb_get_hash_net+0x74/0x12c Status: 11000403 KERNEL EXL IE Cause : 40800010 (ExcCode 04) BadVA : 85144817 PrId : 0001992f (MIPS 1004Kc) Call Trace: [<805e91f0>] __skb_flow_dissect+0x1b0/0x1b50 [<805ead08>] __skb_get_hash_net+0x74/0x12c [<805ef330>] get_rps_cpu+0x1b8/0x3fc [<805fca70>] netif_receive_skb_list_internal+0x324/0x364 [<805fd120>] napi_complete_done+0x68/0x2a4 [<8058de5c>] mtk_napi_rx+0x228/0xfec [<805fd398>] __napi_poll+0x3c/0x1c4 [<805fd754>] napi_threaded_poll_loop+0x234/0x29c [<805fd848>] napi_threaded_poll+0x8c/0xb0 [<80053544>] kthread+0x104/0x12c [<80002bd8>] ret_from_kernel_thread+0x14/0x1c Code: 02d51821 1060045b 00000000 <8c640000> 3084000f 2c820005 144001a2 00042080 8e220000 To reduce the attack surface and maintain performance, do not process PPPoE PFC frames. [1] https://lore.kernel.org/r/[email protected]
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use of Incorrect Byte Ordering
The product receives input from an upstream component, but it does not account for byte ordering (e.g. big-endian and little-endian) when processing the input, causing an incorrect number or value to be used.
More Use of Incorrect Byte Ordering vulnerabilities (CWE-198)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/0d00b9015069712944934bab09eaa6c542143049
- git.kernel.org/stable/c/18ae9eacfc95cc715c0606b2c86e8aa8a86cf3e3
- git.kernel.org/stable/c/6044392d9cace3a3672b02c8bc7d38b502e51734
- git.kernel.org/stable/c/7c93f353eab4ea911e394630f07d72e040a729d8
- git.kernel.org/stable/c/abc5bc84e0f2edc7ea2d437afa6ef3fe1fc43200
- git.kernel.org/stable/c/d6c19b31a3c1d519fabdcf0aa239e6b6109b9473
- git.kernel.org/stable/c/db104b0d8a7856397c0469d83a4289adf7c54863
- git.kernel.org/stable/c/e7c811ca372d53c2be7d01a1614e71fae1054836
Other references
Recent Use of Incorrect Byte Ordering vulnerabilities
- 7.5 High severity
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