CVE-2023-53021

HIGHNVD 7.87.8
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2025-03-27. NVD baseline CVSS 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Trending — 5 sources updated this week

Also known asEUVD-2023-59699 (ENISA EUVD) · GHSA-j94v-m9xh-gwvq (GitHub Security Advisories)Source: ENISA EUVD

7.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 7.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

In the Linux kernel, the following vulnerability has been resolved:

net/sched: sch_taprio: fix possible use-after-free

syzbot reported a nasty crash [1] in net_tx_action() which made little sense until we got a repro.

This repro installs a taprio qdisc, but providing an invalid TCA_RATE attribute.

qdisc_create() has to destroy the just initialized taprio qdisc, and taprio_destroy() is called.

However, the hrtimer used by taprio had already fired, therefore advance_sched() called __netif_schedule().

Then net_tx_action was trying to use a destroyed qdisc.

We can not undo the __netif_schedule(), so we must wait until one cpu serviced the qdisc before we can proceed.

Many thanks to Alexander Potapenko for his help.

[1] BUG: KMSAN: uninit-value in queued_spin_trylock include/asm-generic/qspinlock.h:94 [inline] BUG: KMSAN: uninit-value in do_raw_spin_trylock include/linux/spinlock.h:191 [inline] BUG: KMSAN: uninit-value in __raw_spin_trylock include/linux/spinlock_api_smp.h:89 [inline] BUG: KMSAN: uninit-value in _raw_spin_trylock+0x92/0xa0 kernel/locking/spinlock.c:138 queued_spin_trylock include/asm-generic/qspinlock.h:94 [inline] do_raw_spin_trylock include/linux/spinlock.h:191 [inline] __raw_spin_trylock include/linux/spinlock_api_smp.h:89 [inline] _raw_spin_trylock+0x92/0xa0 kernel/locking/spinlock.c:138 spin_trylock include/linux/spinlock.h:359 [inline] qdisc_run_begin include/net/sch_generic.h:187 [inline] qdisc_run+0xee/0x540 include/net/pkt_sched.h:125 net_tx_action+0x77c/0x9a0 net/core/dev.c:5086 __do_softirq+0x1cc/0x7fb kernel/softirq.c:571 run_ksoftirqd+0x2c/0x50 kernel/softirq.c:934 smpboot_thread_fn+0x554/0x9f0 kernel/smpboot.c:164 kthread+0x31b/0x430 kernel/kthread.c:376 ret_from_fork+0x1f/0x30

Uninit was created at: slab_post_alloc_hook mm/slab.h:732 [inline] slab_alloc_node mm/slub.c:3258 [inline] __kmalloc_node_track_caller+0x814/0x1250 mm/slub.c:4970 kmalloc_reserve net/core/skbuff.c:358 [inline] __alloc_skb+0x346/0xcf0 net/core/skbuff.c:430 alloc_skb include/linux/skbuff.h:1257 [inline] nlmsg_new include/net/netlink.h:953 [inline] netlink_ack+0x5f3/0x12b0 net/netlink/af_netlink.c:2436 netlink_rcv_skb+0x55d/0x6c0 net/netlink/af_netlink.c:2507 rtnetlink_rcv+0x30/0x40 net/core/rtnetlink.c:6108 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0xf3b/0x1270 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x1288/0x1440 net/netlink/af_netlink.c:1921 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg net/socket.c:734 [inline] ____sys_sendmsg+0xabc/0xe90 net/socket.c:2482 ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2536 __sys_sendmsg net/socket.c:2565 [inline] __do_sys_sendmsg net/socket.c:2574 [inline] __se_sys_sendmsg net/socket.c:2572 [inline] __x64_sys_sendmsg+0x367/0x540 net/socket.c:2572 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd

CPU: 0 PID: 13 Comm: ksoftirqd/0 Not tainted 6.0.0-rc2-syzkaller-47461-gac3859c02d7f #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022

CVSS v3
7.8
EG Score
7.8HIGHmedium confidence
EG Risk
35
EG Risk 35/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity78% × 45%
Impact severity (EG Severity): CVSS 7.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.2% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.2%
EPSS %ILE
9th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (7.8): severity, escalated by confirmed exploitation. This CVE's 7.8 is its impact severity (EG Severity), not escalated.

EG Severity
7.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-28). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

March 27, 2025

Last Modified

August 5, 2026

Advisory Details (5)

Auto-updated Aug 4, 2026
Patch available.
Web page

net/sched: sch_taprio: fix possible use-after-free - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/3a415d59c1dbec9d772dbfab2d2520d98360caae
Web page

net/sched: sch_taprio: fix possible use-after-free - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/d3b2d2820a005e43855fa71b80c4a4b194201c60
Web page

net/sched: sch_taprio: fix possible use-after-free - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/c53acbf2facfdfabdc6e6984a1a38f5d38b606a1
Web page

net/sched: sch_taprio: fix possible use-after-free - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/c60fe70078d6e515f424cb868d07e00411b27fbc
Web page

net/sched: sch_taprio: fix possible use-after-free - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/1200388a0b1c3c6fda48d4d2143db8f7e4ef5348

Vendor Advisories for CVE-2023-53021(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(3)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatkernel-0:4.18.0-513.5.1.el8_92023-11-14redhat
redhatkernel-0:5.14.0-284.11.1.el9_22023-05-09redhat
linuxKernel @ 5.4.231 (fixes >=4.20.0)—osv

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
linux5.10.103-1 ... 5.10.92-2 (25 versions)
  • every version up to 5.10.178-1: fixed in 5.10.178-1
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 6.1.11-1: fixed in 6.1.11-1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 6.1.11-1: fixed in 6.1.11-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 6.1.11-1: fixed in 6.1.11-1
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 11× in last 7d / 42× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 94 of 206 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 6 repeat rows among the latest 100 are merged into the row they repeat. The 112 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-02 16:40 UTCEPSS rescoreEPSS 0.2% · 9th percentile
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  6. 2026-10-28 20:48 UTCEG score recompute
  7. 2026-10-28 20:48 UTCVendor advisory
  8. 2026-10-28 20:47 UTCGHSA enrichmentGHSA-j94v-m9xh-gwvq · GitHub severity HIGH · GitHub CVSS 7.8
  9. 2026-10-28 18:55 UTCOSV refresh
  10. 2026-10-28 16:29 UTCEPSS rescoreEPSS 0.2% · 9th percentile
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  19. 2026-10-20 21:16 UTCEG score recompute
  20. 2026-10-20 21:16 UTCVendor advisory
  21. 2026-10-20 21:16 UTCGHSA enrichmentGHSA-j94v-m9xh-gwvq · GitHub severity HIGH · GitHub CVSS 7.8
  22. 2026-10-20 16:30 UTCEPSS rescoreEPSS 0.2% · 8th percentile
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  24. 2026-10-19 14:55 UTCOSV refresh
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  1. 2026-10-18 07:41 UTCEG score recompute
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Frequently asked(5)

What is CVE-2023-53021?
CVE-2023-53021 is a high-severity vulnerability; its CVE record was published on March 27, 2025. In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_taprio: fix possible use-after-free syzbot reported a nasty crash [1] in net_tx_action() which made little sense until we got a repro. This repro installs a taprio qdisc, but providing an invalid TCA_RATE attribute.…
When was the CVE record for CVE-2023-53021 published?
The CVE record for CVE-2023-53021 was published on March 27, 2025. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of August 5, 2026; the record at its source may have been updated since.
Is CVE-2023-53021 actively exploited?
CVE-2023-53021 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (9th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2023-53021?
CVE-2023-53021 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2023-53021?
A fix for CVE-2023-53021 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2023-53021 are linked in the Vendor Advisories panel on this page.

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