CVE-2023-42809

HIGHNVD 8.88.8
EchelonGraph scoreMEDIUM confidence

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

This high-severity CVE scores 8.8 under NVD CVSS v3. EPSS exploit probability: 1.1% (65th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, NVD CVSS v3
Elevated
8.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 1.1%CVSS: 8.8Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

Redisson is a Java Redis client that uses the Netty framework. Prior to version 3.22.0, some of the messages received from the Redis server contain Java objects that the client deserializes without further validation. Attackers that manage to trick clients into communicating with a malicious server can include especially crafted objects in its responses that, once deserialized by the client, force it to execute arbitrary code. This can be abused to take control of the machine the client is running in. Version 3.22.0 contains a patch for this issue.

Some post-fix advice is available. Do NOT use Kryo5Codec as deserialization codec, as it is still vulnerable to arbitrary object deserialization due to the setRegistrationRequired(false) call. On the contrary, KryoCodec is safe to use. The fix applied to SerializationCodec only consists of adding an optional allowlist of class names, even though making this behavior the default is recommended. When instantiating SerializationCodec please use the SerializationCodec(ClassLoader classLoader, Set allowedClasses) constructor to restrict the allowed classes for deserialization.

CVSS v3
8.8
EG Score
8.8HIGHmedium confidence
EG Risk
56
EG Risk 56/100

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)
Severity88% × 45%
Impact severity (EG Severity): CVSS 8.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Track* at medium and Attend at high mission impact.
Exploitation public PoC (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 at low or medium mission impact and sooner than that at high.
EPSS PROB
1.1%
EPSS %ILE
65th
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 (8.8): severity, escalated by confirmed exploitation. This CVE's 8.8 is its impact severity (EG Severity), not escalated.

EG Severity
8.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
1.1% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-20). 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, Track* at medium and Attend at high mission impact.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: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Track* at medium and Attend at high mission impact.

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (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.

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

October 4, 2023

Last Modified

June 17, 2026

Advisory Details (2)

Auto-updated Aug 30, 2026
Patch available. Sources: github_commit, github.
GitHub advisory

GHSL-2023-053: Unsafe deserialization in Redisson - CVE-2023-42809 | GitHub Security Lab

https://securitylab.github.com/advisories/GHSL-2023-053_Redisson/
GitHub commit Patch Available

commit fe6a25718016 (redisson/redisson)

Patch available: redisson/redisson redisson-3.37.0 (contains commit fe6a25718016)

https://github.com/redisson/redisson/commit/fe6a2571801656ff1599ef87bdee20f519a5d1fe

Affected Packages

(1 across 1 ecosystem)
Maven(1)
PackageVulnerable rangeFix by version rangeDependents
org.redisson:redisson0.9.0 ... 3.9.1 (206 versions)
  • every version up to 3.22.0: fixed in 3.22.0
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 33× 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 84 of 200 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. 16 repeat rows among the latest 100 are merged into the row they repeat. The 116 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-22 16:31 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  2. 2026-10-21 16:29 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  3. 2026-10-20 23:11 UTCEG score recompute
  4. 2026-10-20 16:30 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  5. 2026-10-19 16:29 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  6. 2026-10-18 07:51 UTCEG score recompute
  7. 2026-10-17 16:30 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  8. 2026-10-16 16:36 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  9. 2026-10-15 16:29 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  10. 2026-10-14 16:30 UTCEPSS rescoreEPSS 1.1% · 65th percentile
  11. 2026-10-13 16:30 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  12. 2026-10-12 16:46 UTCEG score recompute
  13. 2026-10-12 16:31 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  14. 2026-10-11 21:45 UTCEG score recompute
  15. 2026-10-11 13:45 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  16. 2026-10-10 19:57 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  17. 2026-10-09 20:05 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  18. 2026-10-08 17:06 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  19. 2026-10-07 23:46 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  20. 2026-10-06 15:15 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  21. 2026-10-05 17:41 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  22. 2026-10-04 23:20 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  23. 2026-10-03 14:23 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  24. 2026-10-01 19:48 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  25. 2026-09-30 16:30 UTCEG score recompute
Show 59 more
  1. 2026-09-30 15:01 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  2. 2026-09-29 15:17 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  3. 2026-09-28 13:49 UTCEPSS rescoreEPSS 1.1% · 64th percentile
  4. 2026-09-27 13:42 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  5. 2026-09-26 15:56 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  6. 2026-09-26 00:22 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  7. 2026-09-24 14:01 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  8. 2026-09-23 13:46 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  9. 2026-09-22 22:01 UTCOSV refresh
  10. 2026-09-20 20:14 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  11. 2026-09-18 19:25 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  12. 2026-09-17 19:25 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  13. 2026-09-16 14:06 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  14. 2026-09-16 05:11 UTCEPSS rescoreEPSS 1.0% · 62nd percentile
  15. 2026-09-13 16:44 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  16. 2026-09-12 14:58 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  17. 2026-09-11 14:50 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  18. 2026-09-11 09:34 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  19. 2026-09-08 21:58 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  20. 2026-09-07 15:59 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  21. 2026-09-06 13:45 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  22. 2026-09-05 15:26 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  23. 2026-09-04 13:58 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  24. 2026-09-04 05:04 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  25. 2026-09-03 16:59 UTCOSV refresh
  26. 2026-09-02 14:09 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  27. 2026-09-01 13:51 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  28. 2026-08-30 19:15 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  29. 2026-08-30 01:20 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  30. 2026-08-28 21:39 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  31. 2026-08-27 14:23 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  32. 2026-08-26 14:43 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  33. 2026-08-25 13:46 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  34. 2026-08-23 00:17 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  35. 2026-08-21 23:47 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  36. 2026-08-20 22:53 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  37. 2026-08-19 17:02 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  38. 2026-08-18 13:46 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  39. 2026-08-17 13:45 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  40. 2026-08-17 06:27 UTCOSV refresh
  41. 2026-08-16 14:54 UTCEPSS rescoreEPSS 1.0% · 61st percentile
  42. 2026-08-16 02:12 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  43. 2026-08-15 01:28 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  44. 2026-08-13 21:58 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  45. 2026-08-12 13:48 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  46. 2026-08-11 13:39 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  47. 2026-08-09 13:44 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  48. 2026-08-08 16:35 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  49. 2026-08-07 16:25 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  50. 2026-08-06 13:45 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  51. 2026-08-05 19:15 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  52. 2026-08-04 15:07 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  53. 2026-08-03 10:34 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  54. 2026-08-02 02:25 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  55. 2026-08-02 01:06 UTCOSV refresh
  56. 2026-08-01 04:13 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  57. 2026-07-30 16:26 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  58. 2026-07-30 01:28 UTCEPSS rescoreEPSS 1.0% · 60th percentile
  59. 2026-07-28 15:34 UTCEPSS rescoreEPSS 1.0% · 60th percentile

Frequently asked(5)

What is CVE-2023-42809?
CVE-2023-42809 is a high-severity vulnerability; its CVE record was published on October 4, 2023. Redisson is a Java Redis client that uses the Netty framework. Prior to version 3.22.0, some of the messages received from the Redis server contain Java objects that the client deserializes without further validation. Attackers that manage to trick clients into communicating with a malicious server…
When was the CVE record for CVE-2023-42809 published?
The CVE record for CVE-2023-42809 was published on October 4, 2023. 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 June 17, 2026; the record at its source may have been updated since.
Is CVE-2023-42809 actively exploited?
CVE-2023-42809 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.1% probability of exploitation in the next 30 days (65th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2023-42809?
CVE-2023-42809 has a CVSS v3 base score of 8.8 (NVD).
How do I remediate CVE-2023-42809?
A fix for CVE-2023-42809 is available: update to the fixed version the vendor names in its advisory.

Dependency Blast Radius

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