CVE-2026-53402 — fbdev: fbcon: fix out-of-bounds read in err_out of fbcon_do_set_font()
In the Linux kernel, the following vulnerability has been resolved: fbdev: fbcon: fix out-of-bounds read in err_out of fbcon_do_set_font() When fbcon_do_set_font() fails (e.g., due to a memory allocation failure inside vc_resize() under heavy memory pressure), it jumps to the `err_out` label to roll back the console state. However, the current rollback logic forgets to restore the `hi_font` state, leading to a severe state machine corruption. Earlier in the function, `set_vc_hi_font()` might be called to change `vc->vc_hi_font_mask` and mutate the screen buffer. If `vc_resize()` subsequently fails, the `err_out` path restores `vc_font.charcount` but entirely skips rolling back the `vc_hi_font_mask` and the screen buffer. This mismatch leaves the terminal in a desynchronized state. Because `vc_hi_font_mask` remains set, the VT subsystem will still accept character indices greater than 255 from userspace and write them to the screen buffer. Subsequent rendering calls (e.g., `fbcon_putcs()`) will then use these inflated indices to access the reverted, 256-character font array, leading to a deterministic out-of-bounds read and potential kernel memory disclosure. Fix this by adding the missing rollback logic for the `hi_font` mask and screen buffer in the error path.
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 0.1% (30-day exploitation probability)+0
- Technical severity (high)+6
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.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
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, Linux Linux Kernel).
- Apply the fixed version or the patch documented under Remediation.
- Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Linux | Linux |
version 6.0≥ 5.19.6 and < 5.20≥ 5.15.64 and < 5.15.212≥ 5.10.249 and < 5.10.261version f08ccb792d3eaf1dc62d8cbf6a30d6522329f660≥ a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 and < 8fdc8c2057eea08d40ce2c8eed41ff9e451c65c2≥ a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 and < 39815715cbcfabb16fc8c5f4a23deeda20f5df62≥ a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 and < 076b1aa65f77a49bce5a48a4a55a397cfcafa2b8 and 5 more≥ a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 and < b5bb2c696e140c399cb874def2feedf61dee27d6≥ a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 and < a7a526fbc847f07ad3a503c7382189be5ab68574≥ a5a923038d70d2d4a86cb4e3f32625a5ee6e7e24 and < 3618a4c5b2591cfa83efe74f5b18c2d02b35c3f5≥ ebd6f886aa2447fcfcdce5450c9e1028e1d681bb and < ac562193c36696513ae196171892e9338475c4bc≥ 868749a7456dc48e93887a8474194e2ee6d6c21f and < cb016bcb40c81e7b19c4ae6143babb366dae8e20 |
Vulnerable | CVE Program (cve.org) e CISA ADP |
| Linux | Linux Kernel |
version 6.0-rc7≥ 5.10.249 and < 5.10.261version 6.0-rc6version 6.0-rc5version 6.0-rc4version 6.0-rc3version 6.0≥ 6.19 and < 7.1.3 and 6 more≥ 6.13 and < 6.18.39≥ 6.7 and < 6.12.96≥ 6.2 and < 6.6.145≥ 6.0.1 and < 6.1.178≥ 5.19.6 and < 6.0≥ 5.15.64 and < 5.15.212 |
Vulnerable | NIST National Vulnerability Database |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 7.1 | CVSS 3.1 | High | 1.8 | 5.2 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database |
| 7.1 | CVSS 3.1 | High | — | — | Linux via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H (score shown at the top: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
- Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
Timeline
What happened to this CVE, newest first.
- 2026
- SSVC assessment updated
- Affected products added · linux/linux
- Record published
- Fix documented
- CVSS changed · 7.1
- Source status changed · → Analyzed
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 15, 2026 – Oct 15, 2026
References
8 on the record
- git.kernel.org/stable/c/a7a526fbc847f07ad3a503c7382189be5ab68574
- git.kernel.org/stable/c/cb016bcb40c81e7b19c4ae6143babb366dae8e20
- git.kernel.org/stable/c/076b1aa65f77a49bce5a48a4a55a397cfcafa2b8
- git.kernel.org/stable/c/8fdc8c2057eea08d40ce2c8eed41ff9e451c65c2
- git.kernel.org/stable/c/3618a4c5b2591cfa83efe74f5b18c2d02b35c3f5
- git.kernel.org/stable/c/ac562193c36696513ae196171892e9338475c4bc
- git.kernel.org/stable/c/39815715cbcfabb16fc8c5f4a23deeda20f5df62
- git.kernel.org/stable/c/b5bb2c696e140c399cb874def2feedf61dee27d6
Elsewhere on this site
Related CVEs (same products)
- Critical CVE-2026-99999 ipv4: validate checksum_start before completing checksum 1d
- Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 1d
- Unknown CVE-2026-98424 wifi: cfg80211: undo netns switch if renaming the wiphy fails 2d
- Unknown CVE-2026-98425 wifi: mac80211: don't warn when an IBSS has no channel to scan 2d
- Unknown CVE-2026-98426 wifi: mwifiex: fix IRQ leak using wrong index in MSI-X error path 2d
- Unknown CVE-2026-98427 net/sched: codel: bound the dropping loop per dequeue call 2d
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 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-2026-53402 is "fbdev: fbcon: fix out-of-bounds read in err_out of fbcon_do_set_font()", rated High. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.1 describes technical severity. EPSS 0.14% 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.
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