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CVE-2026-80587— mptcp: avoid combining some incoming suboptions

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

以下是该 Linux 内核漏洞描述的中文翻译： 在 Linux 内核中，以下漏洞已得到修复： mptcp：避免组合某些入站子选项 根据 RFC8684，某些 MPTCP 子选项是互斥的；此外，由于代码在多处并未预期某些组合会同时出现，因此需要加以限制。这一点对于可能以不同属性重复出现两次的子选项尤其重要。 新的限制规则与发送端在 中应用的一致。通过一个小修复，我们可以复用相同的规则：当发送方选择该选项时，MP_FASTCLOSE 可以与 DSS 一起使用[1]，但在 Linux 中并非如此。以下是规则说明： 哪些选

AI Predicted 5.5 Difficulty: Hard

Possible ATT&CK Techniques 1 AI

T1213 · Data from Information Repositories

Affected Version Matrix 12

VendorProduct Version RangeStatus
Linux Linux eda7acddf8080bb2d022a8d4b8b2345eb80c63ec< dc1d8d3eb345c616fbe922a010fa391c72c54d52 affected
eda7acddf8080bb2d022a8d4b8b2345eb80c63ec< 099bfcbd0c16ae9b50aba2a1bea033e63f895da7 affected
eda7acddf8080bb2d022a8d4b8b2345eb80c63ec< a04dcc784959e4702048785d87e0d029bd2fbdcb affected
eda7acddf8080bb2d022a8d4b8b2345eb80c63ec< 6bab907292155513af397a12ccb488acbfc30d79 affected
eda7acddf8080bb2d022a8d4b8b2345eb80c63ec< b6ee361524641f57b2e2363f7737f20e17f67827 affected
5.6 affected
< 5.6 unaffected
6.6.153≤ 6.6.* unaffected
… +4 more rows
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I. Basic Information for CVE-2026-80587

Vulnerability Information
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Vulnerability Title
mptcp: avoid combining some incoming suboptions
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: mptcp: avoid combining some incoming suboptions Some MPTCP suboptions are mutually exclusive according to the RFC8684, but also because in different places, the code doesn't expect some combinations to be present. That's specially true for suboptions that would be present twice, but with different attributes. The new restrictions are the same as the ones applied on the output side, with mptcp_write_options. The same rules can be reused with a small fix: an MP_FASTCLOSE can be used with a DSS when the sender picks this option [1], which is not the case on Linux. Here are the rules: Which options can be used together? X: mutually exclusive O: often used together C: can be used together in some cases P: could be used together but we prefer not to (optimisations) | Opt: | MPC | MPJ | DSS | ADD | RM | PRIO | FAIL | FC | |------|------|------|------|------|------|------|------|------| | MPC |------|------|------|------|------|------|------|------| | MPJ | X |------|------|------|------|------|------|------| | DSS | X | X |------|------|------|------|------|------| | ADD | X | X | P |------|------|------|------|------| | RM | C | C | C | P |------|------|------|------| | PRIO | X | C | C | C | C |------|------|------| | FAIL | X | X | C | X | X | X |------|------| | FC | X | X | P | X | X | X | X |------| | RST | X | X | X | X | X | X | O | O | |------|------|------|------|------|------|------|------|------| The only difference is with the 'P': another stack could send and ADD_ADDR with other suboptions (DSS, RM_ADDR), and this should be allowed. A few points of attention: - In theory, an MP_CAPABLE could be used with a RM_ADDR, but there is no reason to add it with a SYN. Note that even with a 4th ACK, it doesn't seem to be useful, except when IDs are known in advance via another channel. Better not to break that. - Now, combining both an MP_CAPABLE and an MP_JOIN will no longer result to a reject of the two options, but only the second suboption is ignored. That seems OK to do that for this unexpected error. At least now all inconsistent combinations are handled the same way. This could change later in next. This also means the explicit checks for having both MPC + MPJ in subflow.c will now be unreachable. That's fine, they will be removed in a follow-up patch. - In case of conflicting combinations, the extra suboption(s) is/are ignored: having such combinations either means the remote peer is buggy, or is evil. The simplest action is then taken in this case: stop processing the current suboption. - In mp_opt->suboptions, there is also a bit reserved to the checksum, which can be used in an MP_CAPABLE and a DSS. Each time a DSS option can be used in parallel with another option, the checksum can be set, so the verification is combined into a new OPTIONS_MPTCP_DSS macro. - An MP_CAPABLE ACK can carry a Data-Level Length, and an optional Checksum: they are the same as the ones found in a DSS, because a DSS cannot be used in parallel to an MP_CAPABLE. Similarly, even if there is room, a DSS cannot be used with an MP_JOIN.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux eda7acddf8080bb2d022a8d4b8b2345eb80c63ec ~ dc1d8d3eb345c616fbe922a010fa391c72c54d52 -
Linux Linux 5.6 -

II. Public POCs for CVE-2026-80587

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III. Intelligence Information for CVE-2026-80587

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Patches & Fixes for CVE-2026-80587 (5)

Same Patch Batch · Linux · 2026-08-26 · 92 CVEs total

CVE-2026-80557 libceph: fix OOB read in decode_watchers() via missing bounds check
CVE-2026-80553 s390/vfio_ccw: Cancel existing workqueues
CVE-2026-80552 s390/vfio_ccw: Ensure index for read/write regions are within range
CVE-2026-80549 s390/vfio_ccw: Move cp cleanup out of not operational
CVE-2026-80546 s390/zcrypt: Improve CCA CPRB length and overflow checks
CVE-2026-80547 s390/vfio_ccw: Implement a crw lock
CVE-2026-80545 s390/zcrypt: Improve EP11 CPRB length and overflow checks
CVE-2026-80543 s390/zcrypt: Pad trailing CCA or EP11 message with zeros
CVE-2026-80548 s390/vfio_ccw: Selectively expand io_mutex
CVE-2026-80555 s390/vfio_ccw: Free all memory if cp_init() fails
CVE-2026-80554 s390/vfio_ccw: Limit the number of channel program segments
CVE-2026-80556 mmc: atmel-mci: Fix use-after-free in atmci_remove due to race condition
CVE-2026-80559 Input: sur40 - fix input device registration ordering
CVE-2026-80558 libceph: Avoid using invalid osd indices from primary_temp
CVE-2026-80560 openrisc: signal: do not restore privileged SR bits on sigreturn
CVE-2026-80561 libceph: fix multiple unsafe decodes in decode_locker()
CVE-2026-80562 gpio: ml-ioh: use raw_spinlock_t for the register lock
CVE-2026-80563 gpio: sloppy-logic-analyzer: fix use-after-free via debugfs trigger on unbind
CVE-2026-80564 gve: fix NULL dereference due to missing ptp adjfine
CVE-2026-80565 crypto: qce - fix error path in devm_qce_register_algs

Showing top 20 of 92 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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