CVE-2023-54099 — fs: Protect reconfiguration of sb read-write from racing writes
In the Linux kernel, the following vulnerability has been resolved: fs: Protect reconfiguration of sb read-write from racing writes The reconfigure / remount code takes a lot of effort to protect filesystem's reconfiguration code from racing writes on remounting read-only. However during remounting read-only filesystem to read-write mode userspace writes can start immediately once we clear SB_RDONLY flag. This is inconvenient for example for ext4 because we need to do some writes to the filesystem (such as preparation of quota files) before we can take userspace writes so we are clearing SB_RDONLY flag before we are fully ready to accept userpace writes and syzbot has found a way to exploit this [1]. Also as far as I'm reading the code the filesystem remount code was protected from racing writes in the legacy mount path by the mount's MNT_READONLY flag so this is relatively new problem. It is actually fairly easy to protect remount read-write from racing writes using sb->s_readonly_remount flag so let's just do that instead of having to workaround these races in the filesystem code. [1] https://lore.kernel.org/all/00000000000006a0df05f6667499@google.com/T/
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.2% (30-day exploitation probability)+2
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Linux Linux).
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes, errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Linux | Linux | ≥ 8d0347f6c3a9d4953ddd636a31c6584da082e084 and < 0336b42456e485fda1006b5b411e7372e20fbf03≥ 8d0347f6c3a9d4953ddd636a31c6584da082e084 and < 7e4e87ec56aa6d008c64eab31b340a7c452b26cc≥ 8d0347f6c3a9d4953ddd636a31c6584da082e084 and < 0ccfe21949bc9f706a86ee7351b74375c0745757≥ 8d0347f6c3a9d4953ddd636a31c6584da082e084 and < 295ef44a2abaf97d7a594b1d4c60d4be3738191f≥ 8d0347f6c3a9d4953ddd636a31c6584da082e084 and < 4abda85197ba5d695e6040d580b4b409ce0d3733≥ 8d0347f6c3a9d4953ddd636a31c6584da082e084 and < c541dce86c537714b6761a79a969c1623dfa222bversion 5.1 | Vulnerable | CVE Program (cve.org) e CISA ADP |
EPSS over time FIRST
Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.21%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Not enough vector or weakness data: use the affected application’s logs as a starting point.
Timeline
What happened to this CVE, newest first.
- 2026
- Record published
- Affected products added · linux/linux
- Source status changed · → Deferred
- Record created in this database
- 2025
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
6 on the record
- git.kernel.org/stable/c/295ef44a2abaf97d7a594b1d4c60d4be3738191f
- git.kernel.org/stable/c/7e4e87ec56aa6d008c64eab31b340a7c452b26cc
- git.kernel.org/stable/c/0336b42456e485fda1006b5b411e7372e20fbf03
- git.kernel.org/stable/c/0ccfe21949bc9f706a86ee7351b74375c0745757
- git.kernel.org/stable/c/c541dce86c537714b6761a79a969c1623dfa222b
- git.kernel.org/stable/c/4abda85197ba5d695e6040d580b4b409ce0d3733
Elsewhere on this site
Related CVEs (same products)
- Critical CVE-2026-99999 ipv4: validate checksum_start before completing checksum 6h
- Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 6h
- Unknown CVE-2026-98424 wifi: cfg80211: undo netns switch if renaming the wiphy fails 1d
- Unknown CVE-2026-98425 wifi: mac80211: don't warn when an IBSS has no channel to scan 1d
- Unknown CVE-2026-98426 wifi: mwifiex: fix IRQ leak using wrong index in MSI-X error path 1d
- Unknown CVE-2026-98427 net/sched: codel: bound the dropping loop per dequeue call 1d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No CVSS score published by NVD, the CNA, CISA or GitHub so far.
- No fixed version, patch or mitigation documented.
- No CISA SSVC assessment.
- No CWE classification.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2023-54099 is "fs: Protect reconfiguration of sb read-write from racing writes", rated Unknown. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. EPSS 0.21% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
Comments
Moderated technical discussion. Read the community guidelines.
No comments yet.
Sign in or create an account to comment and suggest corrections.