CVE-2021-27439: TencentOS-tiny Integer Overflow or Wraparound
Vulnerability summary
CVE-2021-27439 is a critical (CVSS 9.8) Integer Overflow or Wraparound vulnerability in tencent tencentos-tiny. EPSS estimates a 1.56% chance of exploitation in the next 30 days, higher than 75.2% of scored vulnerabilities.
Severe, CVSS 7.3 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 2% (FIRST, 03-11-2026)
Source freshness unavailable
How is this decided?Timeline
- 03-05-2022PublishedVulnerability first disclosed.
- 16-04-2025Last modifiedVulnerability information updated.
Description
TencentOS-tiny version 3.1.0 is vulnerable to integer wrap-around in function 'tos_mmheap_alloc incorrect calculation of effective memory allocation size. This improper memory assignment can lead to arbitrary memory allocation, resulting in unexpected behavior such as a crash or a remote code injection/execution.
CVSS metrics
3 scores · 2 sources · 2 versions- CVE.orgCNA7.3HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:LDiffers
EPSS trend
Probability
1.56%
Chance of exploitation in the next 30 days
Percentile
75%
Versus all other CVEs
30-day change
No change 0.00 pp
From 1.56% on 04-10-2026
Known exploited
Compare KEV catalogsNot in the CISA KEV catalog.
Not in the ENISA CNW catalog.
Not in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Tencent1 product
- tencentos-tiny3.1.0
Tencentos-tiny1 product
- tencentos-tiny3.1.0
2 vendors · 2 products
References
1 links- www.cisa.gov/uscert/ics/advisories/icsa-21-119-04X Refsource CONFIRMThird Party AdvisoryUS Government Resource