7.5

CVE-2026-39820: Quadratic string concatentation in consumeComment in net/mail

Modified
AliasesRHSA-2026:54883RHSA-2026:57401UBUNTU-CVE-2026-39820
Published 07-05-2026Last modified 18-09-2026

Vulnerability summary

CVE-2026-39820 is a high (CVSS 7.5) vulnerability in go standard library net/mail. EPSS estimates a 0.78% chance of exploitation in the next 30 days, higher than 56% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 7.5 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 1% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
0.78%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 53 · Related 54
OPENSUSE-SU-2026:10723-1OPENSUSE-SU-2026:10741-1OPENSUSE-SU-2026:12166-1OPENSUSE-SU-2026:21254-1OPENSUSE-SU-2026:21319-1OPENSUSE-SU-2026:21483-1

Timeline

  1. 07-05-2026
    PublishedVulnerability first disclosed.
  2. 18-09-2026
    Last modifiedVulnerability information updated.

Description

Well-crafted inputs reaching ParseAddress, ParseAddressList, and ParseDate were able to trigger excessive CPU exhaustion and memory allocations.

CVSS metrics

8 scores · 8 sources · 1 version

EPSS trend

Probability

0.78%

Chance of exploitation in the next 30 days

Percentile

56%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.78% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Chainguard198 products
  • aactl< 0.4.12-r50 | < 0.4.12-r51
  • act< 0.2.88-r2
  • actions-runner-controller-fips< 0.14.1-r2 | < 0.14.1-r1 | All versions (No fix recorded)
  • addon-resizerAll versions (No fix recorded)
  • addon-resizer-fipsAll versions (No fix recorded)
Alpine2 products
  • go≥ 1.26.0, < 1.25.10-r0 | ≥ 1.26.0, < 1.26.3-r0
  • rclone< 1.74.1-r0

2 vendors · 200 products · Showing 200 of 3327

References

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