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.
CVE-2026-72854
“—” 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.
Also known asEUVD-2026-63537 (ENISA EUVD) · GHSA-p5jw-mm77-f8jp (GitHub Security Advisories)Source: ENISA EUVD
- CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
A fix is available — apply it.
- CVSS v3
- 5.3
- EG Score
- 5.3MEDIUMmedium confidence
- EG Risk
- 40EG 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, 2026msgpack-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-reservationGitHub - msgpack/msgpack-c: MessagePack implementation for C and C++ / msgpack.org[C/C++] · GitHub
https://github.com/msgpack/msgpack-cmsgpack-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.cmsgpack-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-L223msgpack-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-L502Integer overflow in msgpack_unpacker_expand_buffer() causes false-success undersized reservation · Issue #1181 · msgpack/msgpack-c · GitHub
https://github.com/msgpack/msgpack-c/issues/1181Vendor Advisories for CVE-2026-72854(2)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(3 across 3 ecosystems)
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| msgpack-c | 4.0.0-3 ... 7.0.1-1 (12 versions) |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| msgpack-c | 6.0.1-3, 6.1.0-1, 6.1.0-2, 7.0.1-1 |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| msgpack-c | 6.0.1-3, 6.1.0-1, 6.1.0-2, 7.0.1-1 |
| — |
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.
- 2026-11-02 16:46 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-29 14:43 UTCEG score recompute
- 2026-10-29 14:43 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
- 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-28 04:25 UTCOSV refresh
- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-25 14:06 UTCEG score recompute
- 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-18 20:36 UTCEG score recompute
- 2026-10-18 20:36 UTCVendor advisory
- 2026-10-18 20:36 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
- 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-18 03:15 UTCEG score recompute
- 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.2% · 4th percentile
Show 75 moreShow fewer
- 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-12 15:41 UTCEG score recompute
- 2026-10-11 19:27 UTCEG score recompute
- 2026-10-11 16:42 UTCEG score recompute
- 2026-10-11 14:02 UTCEG score recompute
- 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-09 08:24 UTCVendor advisory
- 2026-10-09 08:24 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
- 2026-10-08 05:32 UTCEG score recompute
- 2026-10-08 05:32 UTCVendor advisory
- 2026-10-08 05:32 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-07 06:42 UTCEG score recompute
- 2026-10-07 06:42 UTCVendor advisory
- 2026-10-07 06:42 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
- 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-06 07:52 UTCEG score recompute
- 2026-10-06 07:52 UTCVendor advisory
- 2026-10-06 07:52 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
- 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-05 05:00 UTCEG score recompute
- 2026-10-05 05:00 UTCVendor advisory
- 2026-10-05 05:00 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
- 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-04 04:30 UTCEG score recompute
- 2026-10-04 04:30 UTCVendor advisory
- 2026-10-04 04:30 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
- 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-03 05:39 UTCEG score recompute
- 2026-10-03 05:39 UTCVendor advisory
- 2026-10-03 05:39 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
- 2026-10-02 06:49 UTCEG score recompute
- 2026-10-02 06:49 UTCVendor advisory
- 2026-10-02 06:49 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
- 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-10-01 07:03 UTCEG score recompute
- 2026-10-01 07:03 UTCVendor advisory
- 2026-10-01 07:03 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
- 2026-09-30 08:12 UTCEG score recompute
- 2026-09-30 08:12 UTCVendor advisory
- 2026-09-30 08:12 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
- 2026-09-29 01:55 UTCEG score recompute
- 2026-09-29 01:55 UTCVendor advisory
- 2026-09-29 01:55 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
- 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-09-28 02:00 UTCEG score recompute
- 2026-09-28 02:00 UTCVendor advisory
- 2026-09-28 02:00 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
- 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-09-27 02:59 UTCEG score recompute
- 2026-09-27 02:59 UTCVendor advisory
- 2026-09-27 02:59 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
- 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.2% · 4th percentile
- 2026-09-24 20:15 UTCEG score recompute
- 2026-09-24 20:15 UTCVendor advisory
- 2026-09-24 20:15 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
- 2026-09-24 14:58 UTCEG score recompute
- 2026-09-24 14:58 UTCVendor advisory
- 2026-09-24 14:58 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
- 2026-09-23 20:03 UTCEG score recompute
- 2026-09-23 20:03 UTCVendor advisory
- 2026-09-23 20:03 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
- 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-09-22 19:45 UTCEG score recompute
- 2026-09-22 19:45 UTCVendor advisory
- 2026-09-22 19:45 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
- 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.1% · 1st percentile
- 2026-09-21 18:09 UTCVendor advisory
- 2026-09-21 18:09 UTCGHSA enrichmentGHSA-p5jw-mm77-f8jp · GitHub CVSS 5.3
Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-72854?
When was CVE-2026-72854 made public?
Is CVE-2026-72854 actively exploited?
What is the CVSS score of CVE-2026-72854?
How do I remediate CVE-2026-72854?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-72854
Is Your Infrastructure Affected by CVE-2026-72854?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.