CVE-2026-72854

MEDIUMPre-NVD 5.35.3
EchelonGraph scoreMEDIUM confidence

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

Score 5.3 from GitHub Security Advisory published 2026-08-20. A secondary CVSS source baseline 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 4 sources updated this weekElevated

Also known asEUVD-2026-63537 (ENISA EUVD) · GHSA-p5jw-mm77-f8jp (GitHub Security Advisories)Source: ENISA EUVD

5.3EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (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: 0.2%CVSS: 5.3Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

msgpack_unpacker_expand_buffer in src/unpack.c, reached through the public msgpack_unpacker_reserve_buffer API, computes its new buffer size using an unchecked size_t addition of the requested size and the amount already used. The doubling loop guards its own multiplication against overflow, but the addition in the loop condition is unguarded, so a request near SIZE_MAX wraps: the loop condition is already satisfied, the allocation is performed at the small pre-wrap size, and the function returns true. The caller is told the requested capacity was reserved when it was not, so a subsequent write of the requested length overflows the heap buffer. The library's own example/lib_buffer_unpack.c demonstrates the reserve-then-write pattern, and its defensive assert comparing capacity against the request is compiled out under NDEBUG. msgpack-c's own decode entry points do not derive the reservation size from untrusted input, so reaching this requires an integration that passes an attacker-influenced length to the reservation API, such as a length-prefixed streaming transport.

CVSS v3
5.3
EG Score
5.3MEDIUMmedium confidence
EG Risk
40
EG Risk 40/100

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)
Severity53% × 45%
Impact severity (EG Severity): CVSS 5.3 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 or medium mission impact; Track* at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (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
4th
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 (5.3): severity, escalated by confirmed exploitation. This CVE's 5.3 is its impact severity (EG Severity), not escalated.

EG Severity
5.3 MEDIUMCVSS-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: 60 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 public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (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)60 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 partial (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

August 20, 2026

Last Modified

October 18, 2026

Advisory Details (6)

Auto-updated Aug 20, 2026
Patch available.
Web page

msgpack-c Integer Overflow in msgpack_unpacker_expand_buffer Causes a False-Success Undersized Reservation | Advisories | VulnCheck

https://www.vulncheck.com/advisories/msgpack-c-integer-overflow-in-msgpack-unpacker-expand-buffer-causes-a-false-success-undersized-reservation
Web page

GitHub - msgpack/msgpack-c: MessagePack implementation for C and C++ / msgpack.org[C/C++] · GitHub

https://github.com/msgpack/msgpack-c
Web page

msgpack-c/example/lib_buffer_unpack.c at c-7.0.1 · msgpack/msgpack-c · GitHub

https://github.com/msgpack/msgpack-c/blob/c-7.0.1/example/lib_buffer_unpack.c
Web page

msgpack-c/include/msgpack/unpack.h at c-7.0.1 · msgpack/msgpack-c · GitHub

https://github.com/msgpack/msgpack-c/blob/c-7.0.1/include/msgpack/unpack.h#L219-L223
Web page

msgpack-c/src/unpack.c at c-7.0.1 · msgpack/msgpack-c · GitHub

https://github.com/msgpack/msgpack-c/blob/c-7.0.1/src/unpack.c#L429-L502
Web page

Integer overflow in msgpack_unpacker_expand_buffer() causes false-success undersized reservation · Issue #1181 · msgpack/msgpack-c · GitHub

https://github.com/msgpack/msgpack-c/issues/1181

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
msgpack-c4.0.0-3 ... 7.0.1-1 (12 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
msgpack-c6.0.1-3, 6.1.0-1, 6.1.0-2, 7.0.1-1
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
msgpack-c6.0.1-3, 6.1.0-1, 6.1.0-2, 7.0.1-1
  • every version on: no fix on record
—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 10× in last 7d / 58× 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 100 of 192 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. None are among the latest 100 rows. The 92 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-02 16:46 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  2. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  3. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  4. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  5. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  6. 2026-10-29 14:43 UTCEG score recompute
  7. 2026-10-29 14:43 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
  8. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  9. 2026-10-28 04:25 UTCOSV refresh
  10. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  11. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  12. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  13. 2026-10-25 14:06 UTCEG score recompute
  14. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  15. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  16. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  17. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  18. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  19. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  20. 2026-10-18 20:36 UTCEG score recompute
  21. 2026-10-18 20:36 UTCVendor advisory
  22. 2026-10-18 20:36 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
  23. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  24. 2026-10-18 03:15 UTCEG score recompute
  25. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.2% · 4th percentile
Show 75 more
  1. 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  2. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  3. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  4. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  5. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  6. 2026-10-12 15:41 UTCEG score recompute
  7. 2026-10-11 19:27 UTCEG score recompute
  8. 2026-10-11 16:42 UTCEG score recompute
  9. 2026-10-11 14:02 UTCEG score recompute
  10. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  11. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  12. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  13. 2026-10-09 08:24 UTCVendor advisory
  14. 2026-10-09 08:24 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
  15. 2026-10-08 05:32 UTCEG score recompute
  16. 2026-10-08 05:32 UTCVendor advisory
  17. 2026-10-08 05:32 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
  18. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  19. 2026-10-07 06:42 UTCEG score recompute
  20. 2026-10-07 06:42 UTCVendor advisory
  21. 2026-10-07 06:42 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
  22. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  23. 2026-10-06 07:52 UTCEG score recompute
  24. 2026-10-06 07:52 UTCVendor advisory
  25. 2026-10-06 07:52 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
  26. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  27. 2026-10-05 05:00 UTCEG score recompute
  28. 2026-10-05 05:00 UTCVendor advisory
  29. 2026-10-05 05:00 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
  30. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  31. 2026-10-04 04:30 UTCEG score recompute
  32. 2026-10-04 04:30 UTCVendor advisory
  33. 2026-10-04 04:30 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
  34. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  35. 2026-10-03 05:39 UTCEG score recompute
  36. 2026-10-03 05:39 UTCVendor advisory
  37. 2026-10-03 05:39 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
  38. 2026-10-02 06:49 UTCEG score recompute
  39. 2026-10-02 06:49 UTCVendor advisory
  40. 2026-10-02 06:49 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
  41. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  42. 2026-10-01 07:03 UTCEG score recompute
  43. 2026-10-01 07:03 UTCVendor advisory
  44. 2026-10-01 07:03 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
  45. 2026-09-30 08:12 UTCEG score recompute
  46. 2026-09-30 08:12 UTCVendor advisory
  47. 2026-09-30 08:12 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
  48. 2026-09-29 01:55 UTCEG score recompute
  49. 2026-09-29 01:55 UTCVendor advisory
  50. 2026-09-29 01:55 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
  51. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  52. 2026-09-28 02:00 UTCEG score recompute
  53. 2026-09-28 02:00 UTCVendor advisory
  54. 2026-09-28 02:00 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
  55. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  56. 2026-09-27 02:59 UTCEG score recompute
  57. 2026-09-27 02:59 UTCVendor advisory
  58. 2026-09-27 02:59 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
  59. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  60. 2026-09-24 20:15 UTCEG score recompute
  61. 2026-09-24 20:15 UTCVendor advisory
  62. 2026-09-24 20:15 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
  63. 2026-09-24 14:58 UTCEG score recompute
  64. 2026-09-24 14:58 UTCVendor advisory
  65. 2026-09-24 14:58 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
  66. 2026-09-23 20:03 UTCEG score recompute
  67. 2026-09-23 20:03 UTCVendor advisory
  68. 2026-09-23 20:03 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
  69. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  70. 2026-09-22 19:45 UTCEG score recompute
  71. 2026-09-22 19:45 UTCVendor advisory
  72. 2026-09-22 19:45 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
  73. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  74. 2026-09-21 18:09 UTCVendor advisory
  75. 2026-09-21 18:09 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3

Frequently asked(5)

What is CVE-2026-72854?
CVE-2026-72854 is a medium-severity vulnerability; its CVE record was published on August 20, 2026. msgpack_unpacker_expand_buffer in src/unpack.c, reached through the public msgpack_unpacker_reserve_buffer API, computes its new buffer size using an unchecked size_t addition of the requested size and the amount already used. The doubling loop guards its own multiplication against overflow, but…
When was CVE-2026-72854 made public?
CVE-2026-72854 was made public on August 13, 2026: that is the date its CVE record's CNA, VulnCheck, gives for when the vulnerability was made public. The CVE record itself was published on August 20, 2026. EchelonGraph's copy of the record carries a last-modified date of October 18, 2026; the record at its source may have been updated since.
Is CVE-2026-72854 actively exploited?
CVE-2026-72854 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (4th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-72854?
CVE-2026-72854 has a CVSS base score of 5.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-72854?
A fix for CVE-2026-72854 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-72854 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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