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Vulnerability record · CVE-2026-64089 · published 19 July 2026

CVE-2026-64089: Linux kernel vulnerability

Linux · Linux Kernel

In the Linux kernel, the following vulnerability has been resolved: batman-adv: tt: fix negative last_changeset_len batadv_piv_tt::last_changeset_len len was declared as s16, but the field is never intended to hold a negative value. When a value greater than 32767 is assigned, it wraps to a negative signed integer. In batadv_send_my_tt_response(), last_changeset_len is temporarily widened to s32. The incorrectly negative s16 value propagates into the s32, causing batadv_tt_prepare_tvlv_local_data() to allocate a full sized buffer but populates only a small portion of it with the collected changeset. All remaining bits are kept uninitialized. Using an u16 avoids this type confusion and ensures that no (negative) sign extension is performed in batadv_send_my_tt_response().

9.8 CVSS 3.1 Critical EPSS 0.55% · top 56.1%
9.8CVSS 3.1 base score
0.55%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
8References
11 Aug 2026Last modified by NVD

Description

In the Linux kernel, the following vulnerability has been resolved: batman-adv: tt: fix negative last_changeset_len batadv_piv_tt::last_changeset_len len was declared as s16, but the field is never intended to hold a negative value. When a value greater than 32767 is assigned, it wraps to a negative signed integer. In batadv_send_my_tt_response(), last_changeset_len is temporarily widened to s32. The incorrectly negative s16 value propagates into the s32, causing batadv_tt_prepare_tvlv_local_data() to allocate a full sized buffer but populates only a small portion of it with the collected changeset. All remaining bits are kept uninitialized. Using an u16 avoids this type confusion and ensures that no (negative) sign extension is performed in batadv_send_my_tt_response().

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://git.kernel.org/stable/c/179eb62506a02d00370bd6478898cb632e10986c Patch
https://git.kernel.org/stable/c/22d59c72f4a47ffec121d0610f70d0d70c3c11c8 Patch
https://git.kernel.org/stable/c/55dc41fe8821e9a849e147255ad572bc933a9d15 Patch
https://git.kernel.org/stable/c/6314089acf0ddf64376fdc0b1420695504c73f52 Patch
https://git.kernel.org/stable/c/c424e8519ac78eac5d9f4eecf06208a0d619ec14 Patch
https://git.kernel.org/stable/c/d29abf70c665730e249d2ec8e1402095ae26bcee Patch
https://git.kernel.org/stable/c/eb235472b52ef36981c5aad330485eaf2382c53b Patch
https://git.kernel.org/stable/c/fc92cdfcb295cefa4344d71a527d61b638b7bfc4 Patch

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Source: NIST National Vulnerability Database (record CVE-2026-64089), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.