VulnerabilityPublished 13 Apr 2026Updated 5 Nov 2026

CVE-2026-31423: Linux kernel · net/sched: sch_hfsc: fix divide-by-zero in rtsc_min()

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in d0aefec1b1a1ba2c1d251028dc2c4e5b4ce1fea5 : update Linux kernel when convenient.

Data as of 5 Nov 2026, 21:49 UTC

Severity

Unrated

Rated by Threat Radar · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-11-05.

Patch

Available – fixed in d0aefec1b1a1ba2c1d251028dc2c4e5b4ce1fea5, c56f78614e7781aaceca9bd3cb2128bf7d45c3bd, b9e6431cbea8bb1fae8069ed099b4ee100499835 +5

Exploitation evidence

Disclosed: evidence found.
CVE published 13 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < d0aefec1b1a1ba2c1d251028dc2c4e5b4ce1fea5	Fixed in d0aefec1b1a1ba2c1d251028dc2c4e5b4ce1fea5
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < c56f78614e7781aaceca9bd3cb2128bf7d45c3bd	Fixed in c56f78614e7781aaceca9bd3cb2128bf7d45c3bd
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < b9e6431cbea8bb1fae8069ed099b4ee100499835	Fixed in b9e6431cbea8bb1fae8069ed099b4ee100499835
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < ad8e8fec40290a8c8cf145c0deaadf76f80c5163	Fixed in ad8e8fec40290a8c8cf145c0deaadf76f80c5163
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < ab1ff5890c7354afc7be56502fcfbd61f3b7ae4f	Fixed in ab1ff5890c7354afc7be56502fcfbd61f3b7ae4f
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 4576100b8cd03118267513cafacde164b498b322	Fixed in 4576100b8cd03118267513cafacde164b498b322

Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_hfsc: fix divide-by-zero in rtsc_min() m2sm() converts a u32 slope to a u64 scaled value. For large inputs (e.g. m1=4000000000), the result can reach 2^32. rtsc_min() stores the difference of two such u64 values in a u32 variable `dsm` and uses it as a divisor. When the difference is exactly 2^32 the truncation yields zero, causing a divide-by-zero oops in the concave-curve intersection path: Oops: divide error: 0000 RIP: 0010:rtsc_min (net/sched/sch_hfsc.c:601) Call Trace: init_ed (net/sched/sch_hfsc.c:629) hfsc_enqueue (net/sched/sch_hfsc.c:1569) [...] Widen `dsm` to u64 and replace do_div() with div64_u64() so the full difference is preserved.

References

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