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CVE-2026-64313
crypto: ecc - Fix carry overflow in vli multiplication
Published 2026-07-25 (3 months ago) by the Linux kernel CNA. Subsystem crypto. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-64313 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixedDLA-4720-1 · 2026-08-05 · text | 6.1.180-1 | Update the kernel and reboot. DLA-4720-1 shipped the fix on 2026-08-05, in 6.1.180-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.96-1 | Update the kernel and reboot. Fixed in 6.12.96-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.4-1 | Update the kernel and reboot. Fixed in 7.1.4-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.4-1 | Update the kernel and reboot. Fixed in 7.1.4-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4724-1 · 2026-08-07 · text | 6.12.100-1~deb12u1 | Update the kernel and reboot. DLA-4724-1 shipped the fix on 2026-08-07, in 6.12.100-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The carry flag calculation fails when r01.m_high is saturated (0xFFFFFFFFFFFFFFFF) and addition of lower bits overflows. The condition (r01.m_high < product.m_high) doesn't handle the case where r01.m_high == product.m_high and an additional carry exists from lower-bit overflow. When commit 3c4b23901a0c ("crypto: ecdh - Add ECDH software support") introduced crypto/ecc.c, it split the muladd() function in the micro-ecc library into separate mul_64_64() and add_128_128() helpers. It seems the check got lost in translation. Add proper handling for this boundary by accounting for the carry from the lower addition.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
crypto/ecc.c
- What this is
- ASYMMETRIC KEYS - ECDSAMAINTAINERS section matched on crypto/ecc* · linux-crypto@vger.kernel.org · Maintained
- Kernel module
- ecc
Check it on the machine
grep -w CONFIG_CRYPTO_ECC /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w eccPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this code. Every release below compiles the affected file into the kernels it ships.
- bookwormm
- trixie, forky, sid, bookworm · linux-6.12y
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- y
- built into the kernel image on every flavour - only a patch removes it
- Build switch
- CONFIG_CRYPTO_ECC
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-07-25 (3 months ago)source
- CVSS
- 8.8 high
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- adjacent network (AV:A)source
- EPSS
- 0.35%, higher than 27.6% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- crypto
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.8 | 5.10.261 | d11b2bb99bec |
| 4.8 | 5.15.212 | b709e0e76876 |
| 4.8 | 6.1.178 | 24a54dfa06d0 |
| 4.8 | 6.6.145 | 677450e5ef85 |
| 4.8 | 6.12.96 | 5275e0fca256 |
| 4.8 | 6.18.39 | 774ddddf5eb2 |
| 4.8 | 7.1.4 | ebaae7c4251c |
| 4.8 | 7.2 | 27b536a2ec8e |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4724-1 | 2026-08-07 | bookworm 6.12.100-1~deb12u1 | tracker |
| DLA-4723-1 | 2026-08-07 | bullseye 6.1.180-1~deb11u1 | tracker |
| DLA-4720-1 | 2026-08-05 | bookworm 6.1.180-1 | tracker |
| DLA-4717-1 | 2026-08-05 | bullseye 5.10.262-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:AAttack vector, adjacent network
- The concrete unauthenticated external path is Bluetooth LE Secure Connections, where a nearby peer's SMP Public Key message reaches the flawed ECC multiplication. Bluetooth requires proximity rather than routable network access.
- AC:LAttack complexity, low
- The attacker controls the ECC operands and can repeatedly submit deliberately constructed values that trigger the carry error. No race, unpredictable memory layout, or victim-controlled state is required.
- PR:NPrivileges required, none
- SMP permits a peer to negotiate Secure Connections and submit its public key before credential validation, DHKey confirmation, or bonding completes. No local account or capability is required.
- UI:NUser interaction, none
- The peer's public key is validated and the ECDH secret is computed before authentication-method completion. Headless and Just Works deployments require no human action.
- S:UScope, unchanged
- The vulnerable arithmetic and affected cryptographic consumers operate within the same kernel security authority. The vulnerability does not inherently cross a VM, IOMMU, or comparable security boundary.
- C:HConfidentiality impact, high
- Incorrect field multiplication can undermine public-key validation and ECDH shared-secret computation. Faulty-curve or key-agreement attacks could expose secrets and all data protected by derived session keys.
- I:HIntegrity impact, high
- The same faulty multiplication supports ECDSA and ECRDSA verification, making false cryptographic results and signature or peer-authentication bypass defensible. This can authorize attacker-controlled content, code, or commands.
- A:HAvailability impact, high
- Authentication bypass can authorize attacker-controlled code or commands capable of halting the system, while repeated crafted exchanges can prevent secure pairing. Safety-critical or headless devices dependent on the affected trust path can lose their protected function completely.